Penis Extenders: Essential Facts

Close up of a fully assembled SizeGenetics penis extender

A medically certified penis extender built by DanaMedic and sold under the SizeGenetics brand name.

It’s impossible to ignore the clinical evidence supporting the effectiveness of penis extenders.

Over the last few years, reams of medical research has shown men achieving whopping penile length increases of around 30 percent with consistent use over 3 – 6 months.

What’s more, this isn’t skewed evidence presented by the manufacturers themselves in an attempt to legitimize their products.

Instead, these are independently performed studies published in leading peer-reviewed medical journals including the British Journal of Urology and the Journal of Sexual Medicine (you’ll find more on this medical research below).

How Penis Extenders Work

Penis extenders work through a very simple principle. They apply relatively low levels of tension – usually of between 1.2kg – 2.5kg – to the penile shaft.

In turn, this encourages two independent physiological processes to kick in, both of which stimulate permanent penile growth:

Stretching the Penile Ligaments

Illustration of the suspensory ligament at the base of the penile shaft.

Penis extenders help to stretch the suspensory ligament at the base of the penis. This enables more of the penile shaft to be pulled into view.

Firstly, penis extenders help to stretch the ligaments (called the suspensory and fundiform ligaments) at the bottom of the penile shaft.

This is vital to the enlargement process because by stretching the ligaments, a portion of the 4 – 6 inches of penile shaft that usually hides inside the body can be gradually pulled forward into view.

If you don’t believe how much of your penis is hidden inside your body, just have a poke behind your scrotum the next time you get an erection. You can easily feel how much of the penile shaft is hidden away there.

In fact, you may already know that penile lengthening surgery involves cutting these ligaments – a procedure that works better in theory than in practice.

One of the many problems faced by men who opt for surgery is that during healing, a build up of scar tissue tends to create a ‘false ligament’ which pulls the penis back inside the body.

But as the medical data has shown, cutting the ligaments is unnecessary. Thanks to their natural elasticity, the ligaments possess a significant capacity to stretch, whilst maintaining full functionality.

As a result, penis traction seems to produce in practice what surgery only achieves in theory – an effective elongation of the ligaments, which encourages a gradual exposure of the hidden penis and consequently, a visible increase in penis length.

Cell Multiplication (Hyperplasia)

This consistent stretching also encourages a physiological process known as hyperplasia – a process whereby tissue cells multiply (increasing tissue mass)  in response to physical stress.

Hyperplasia occurs as tissue attempts to better compensate for the additional stress it’s placed under.

Of course, we’re all aware of how resistance training exploits the process of hyperplasia to result in increased muscle mass. But hyperplasia isn’t just confined to the stimulation of muscle growth. In fact, all tissue types are equally susceptible to the process – even bone.

To that end, it’s a physiological response that’s often exploited by orthopedic medicine – where surgeons apply traction to gradually straighten or lengthen the limbs of patients suffering from growth deficiencies or abnormalities.

Fortunately of course, the penis doesn’t contain bone, which makes it a great deal more susceptible to positive growth through hyperplasia.

Medical Trials

As I mentions above, penis extenders have been the subject of a great deal of research – so below I’ve outlined the results of two well-known, peer-reviewed medical trials.

Because these studies were ‘peer reviewed’ i.e. they were scrutinised by third-party doctors, we can be pretty confident that the results are both unbiased and accurate.

Medical Study #1

Bar chart illustration of SizeGenetics clinical results.

The results of published clinical trials illustrating the powerful effects of using the SizeGenetics penis extender – an average 29 percent increase in erect penis length over the course of 24 weeks.

One of the first detailed studies to examine the effectiveness of penile traction was conducted by a Danish physician Dr. Jørn Ege Siana in 1998.

The study, which has been corroborated by a series of subsequent studies, was initially published in the Journal of Sexual Medicine.

This 24 week trial, which involved 18 men from their 20′s to their 40′s using the SizeGenetics (product overview) penis extender, recorded the following results.

  • An average increase of 13 percent in erect length after 8 weeks.
  • An average increase of 2.8 cm (1.1 inches) in erect length after 16 weeks (1100 hrs usage).
  • At the end of the 24 week trial, the average gain in erect length had shot up to 29 percent.
  • Participants gained on average 1.9mm per week – equating to 4.56 cm (1.8 inches) in erect length over the entire 24 weeks of treatment.
  • The biggest erect length reported in the trial came in at a monumental 40 percent.
  • Average gains in erect penis girth were more modest, but still significant, at 0.75 inches.

The only downside to the trial was that in order to achieve these impressive results, the patients used the traction device for 12 hours a day.

Going by these results, a man with a typical 6.4 inch penis could expect to increase his erect length to 8.26 inches.

In percentage terms, that would endow him with a bigger penis than 90 percent of men… a pretty good return on investment for just 24 weeks effort. :-)

Medical Study #2

Although medical grade penis extenders are designed to be worn comfortably for up to 12 hours each day, it’s obviously understandable if you’d prefer not to spend quite so much time with the device on.

Fortunately, another study conducted by urologists at San Giovanni Battista Hospital, Italy and published in the British Journal of Urology in 2008 gives us a good idea of what can be achieved through more moderate daily usage.

In this study 15 men employed the use of a medical grade penis extender for just 4 hours a day over six months (just a third of the time in comparison to the previous study).

Six months later the study’s 15 participants had achieved:

  • An average flaccid length increase of 0.9 inches
  • An average erect length increase of 0.65 inches.

The authors of the study concluded that their results showed that the use of penile traction was a ‘minimally invasive and effective treatment option’ for those looking for a natural alternative to lengthening surgery.

Longer Wearing Time Per Day = Quicker Gains

What you’ll probably have noticed from this later study is that the participants achieved about a third of the length gains that were reported in the first study.

Why? Because they wore the device for a third of the total time.

This is a finding that’s been corroborated in numerous clinical trials: Results achieved through penile traction tend to be directly proportional to the length of time the device is worn per day.

In other words, the more you wear a medically certified device each day, the quicker you’ll see results.

Daily wearing times don’t affect overall results. For example, you’ll achieve exactly the same length increases by using traction for 8 hours per day over 12 weeks as you’d achieve through 4 hours a day over 24 weeks.

It’s simply how quickly you knock up those hours that determines the rapidity of results. In fact, most studies indicate that traction produces penile length gains at a rate of 1 inch for every 1000 hours wearing time.

The other point both these studies undoubtedly confirm of course, is that penile traction is extremely effective.

Better than surgery?

So how does using a penis extender compare to undergoing penis lengthening surgery?

In 2006, a study published in the European Urology journal reported that the average gain in erect length of 42 patients who’d undergone lengthening surgery was just 0.5 inches.

Furthermore, the study noted that approximately 5 percent of men ultimately ended up around half an inch shorter than they were before surgery. Why? Well, as I mentioned at the beginning of this article, penile shortening is a potential danger of this procedure; because during the healing process, the formation of inelastic scar tissue pulls the penis back inside the body.

One of the most interesting observations made by the researchers was that the best results were achieved by ‘some motivated patients’ who’d used a penis extender device during the healing phase – which produced gains of up to 3 cm (1.18 inches).

So the real question is, were those results produced by the surgery or the post-operative use of the penis extender? My guess is that it was probably the extender.

Safety Issues

Independent medical studies have reported no adverse complications or injuries arising from the use of a penis extender.

It’s important to remember however, that these studies all used medically developed devices – developed to provide exactly the right amounts of stretching force to produce optimum gains, whilst maintaining safety.

Their anatomically correct designs also ensure that they can be worn comfortably for extended periods of time without causing problems.

For example, the attachment systems used on medically approved devices ensure that penile blood flow isn’t restricted during use, or that undue pressure is placed on the dorsal nerve running down the penile shaft. Non-certified devices have a habit of causing both these problems; leading not only to discomfort, but a very cold, numb penis too.

At present only two medically certified devices are available – the Jes-Extender by DanaMedic (marketed under the SizeGenetics brand name) and the AndroPenis by AndroMedical.

Both these devices are designed with safety, comfort and durability in mind – features that will ultimately provide you with significantly better results.

Which Device Should You Choose?

This is something I bet you don’t know:

You’ve probably seen a zillion penis extenders for sale all with different names – Jes-Extender, AndroPenis, Pro Extender, SizeGenetics, Vimax Extender, Euro Extender, X4 Labs, Pro Sizer, Ultimate Stretcher etc. etc. to name but a few.

What you probably don’t know is that most of these websites are resellers of just two products:

  1. DanaMedic’s Jes Extender – Sold primarily under the SizeGenetics brand name
  2. AndroMedical’s AndroPenis (Vimax, Euro Extender etc).

Why do they all resell the same two devices?

Basically, because the Jes Extender and AndroPenis are the only medically certified devices available – they’re the ones that have been used with success in all the medical trials.

So when you see the phrase ‘type 1 medical device’ on a website, you know you’re buying one of these two devices. If a website doesn’t mention this, then in all likelihood you’re buying an imitation – which you don’t want to do for obvious reasons, including lack of known safety, durability and effectiveness.

Now the problem is, a lot of the reseller websites will ship out whatever they have in stock – be it the Jes Extender or AndroPenis – so in reality you can’t tell with any certainty what device you’re buying. Neither will you know if it’s the latest specification device or one which they had lying around since 2007.

Not a particularly good prospect when you’ve just invested a load of time researching each brand of penis extender, then spent $300 – 500 on what you think is a specific product, just to end up with something you didn’t expect.

That’s why it’s essential to only ever buy from one of the handful of well-established, reputable resellers – the ones who supply the exact model they display on their websites.

Which is the Best – AndroPenis or Jes Extender?

I’ve bought both, and as far as I’m concerned it’s the Jes Extender – sold by SizeGenetics.

The first thing that has to be said is that both devices are extremely well-built, both have done equally well in clinical trials and both are certified as medical equipment. They even work in mechanically the same way.

But there are a couple of reasons I’m NOT keen on the AndroPenis:

  • Fiddly to assemble: I’m a big believer in KIS ‘Keep it Simple’. Unfortunately, with AndroPenis there are A LOT of fiddly small parts to contend with. If you want to spend the best part of a day learning how to stick the thing together that’s fine – but it’s not for me.
  • Requires frequent re-securing: The extension rods, which run down each side of the penis, have a habit of unscrewing themselves during use. Because of this a lot of AndroPenis users end up having to secure the rods with tape.
  • Outdated method of attachment: Some AndroPenis models still rely on the old style silicone noose method of attachment. The problem here is twofold: 1). They can dig in just behind the head of your penis – cutting off circulation – leading to a very cold/numb penile head and 2). The end of your penis has a habit of slipping out of the noose every few minutes – which is just annoying.
  • Stock uncertainty: If you buy through one of the many AndroPenis resellers you really won’t know whether you’ll end up with the noose or new comfort version. My guess is for the foreseeable future it will be the noose version because it’s cheaper.

So, as I mentioned above, in my opinion the better choice is the Jes Extender.

The Jes Extender

Jes Extender Titanium in flightcase.

The Jes Extender Titanium – a perfectly engineered and medically certified penis extender.

The Jes Extender is the device sold by SizeGenetics .

This was the first medically developed penis extender to be made directly available to the public – way back in 1997. To date, DanaMedic reports that over 250,000 Jes-Extenders have been manufactured – most sold under the SizeGenetics brand name – making this device by far the most popular on the market.

Of course, as you’d expect from a medically certified device, it’s extremely well-built, provides very accurate and safe levels of traction; and it has been clinically shown to work.

  • The 1998 study mentioned above recorded an average increase of 29 percent in erect length over the course of 6 months using the Jes Extender – achieved at an average of 1.9mm per week.
  • Another Jes Extender based study conducted in 2001 and presented at The International Congress of Urologists recorded an average net increase of 3.03 cm (1.19 inches) over just a 17 week period of use.

These studies however, were all conducted before the introduction of DanaMedic’s new innovative ‘comfort strap’ – a development that makes the Jes Extender even more reliable and easier to use than before.

Comparison of the SizeGenetics comfort strap to the standard silicone noose design

What’s so Different about the Comfort Strap?

The comfort strap fitted to all new SizeGenetics Jes Extenders replaces the traditional ‘silicone noose’ that most extenders still use to attach the head of the penis to the device. It’s a very simple idea, but it’s extremely effective for a few reasons:

  • Simple to use: Its one-piece design makes it very simple to put on and take off. Feeding the penile head through the alternative silicone noose is a fiddly and sometimes painful process because the penile skin has a habit of getting pinched as you tighten the noose.
  • Secure attachment: The comfort strap also keeps the head of your penis attached very securely. Because of this you can really crank up the tension to maximum without worrying about the device slipping off. Consistent usage is massively important for maximising gains; and the extremely reliable grip of the comfort strap ensures the device requires little monitoring or readjusting.
  • Evenly distributed, firmer tension: You feel a much better stretch all the way along the length of the penile shaft with the comfort strap. With the noose versions on the other hand, you tend to feel most of the resistance just behind the head of your penis. This can be disconcerting, as it feels as if the noose is slowly slipping off. Often, the only remedy is to apply less tension to compensate.
  • More comfortable: As the name suggests the ‘comfort strap’ feels a great deal more comfortable – you don’t have a thin bit of silicone digging into your penis. Success with penile traction is all down to accumulated wearing time – approximately 1 inch for every 1,000 usage. Increased comfort obviously encourages longer wearing time.
  • Safe: The new comfort strap design doesn’t restrict circulation to the tip of your penis like the traditional silicone noose does. Because of that you can leave it on for extended periods of time without the end of your penis going cold and numb.

I’ve tried both the silicone noose and new comfort strap method of attachment; and because of the above points, the comfort strap makes a BIG different.

Remember: the more you wear the device each day and the greater the level of traction you use, the quicker you’ll see substantial gains in length. So ultimately all the above benefits of the new comfort strap design equate to better gains in less time.

So the key advantages of the Jes-Extender in my opinion are:

  • It stays in place
  • It’s comfortable to wear
  • It provides very consistent levels of traction
  • It’s not as fiddly as the AndroPenis
  • Its medical grade materials are very durable
  • It’s medically designed, tested and certified.

SizeGenetics Jes Extender

At present, it would be hard to justify buying a medically approved penis extender from anywhere other than SizeGenetics.

Not only do they provide the most innovative, powerful extender device available  - in terms of reliability, durability, comfort and ease of use – but their ‘Ultimate Package’ is jam packed with every conceivable upgrade you need to enlarge your penis as efficiently as possible.

What’s more, SizeGenetics Jes-Extenders are the most powerful devices on the market – they’re upgraded from the standard 1500g maximum tension to a massive 2.3 kg. So a Jes Extender is like the Ferrari 360; whilst the SizeGenetics Jes Extender is like a hot rod Ferrari 360 with 100BHP more.

Of course, all that extra power – accompanied with an incredibly secure attachment system – means one thing: quicker, more pronounced results.

SizeGenetics Ultimate Package

The SizeGenetics Ultimate Package: Offering an upgraded Jes-Extender with substantially more tension and the complete 58-piece comfort system. The upgrades deliver a more powerful device with superglue-like attachment and hassle free use. All for just $40 more than a standard Jes-Extender. Even delivery is thrown in for free.

Key Points About SizeGenetics:

Just some of the reasons the SizeGenetics package offers such tremendous value for money include:

Complete accessory pack: SizeGenetics throw in a massive number of spares. For example, they include the complete 58 piece comfort system that costs well over $200 if bought as an accessory directly from DanaMedic.

This in particular, is a massive bonus, because it absolutely ensures that you’ll find the perfect way to secure the device to your penis – regardless of size, whether your circumcised etc. The more comfortable and secure the device is of course, the more you’ll wear it; and as we’ve seen in through above studies, maximizing wearing time is all important when it comes to achieving rapid gains.

Extremely powerful: The SizeGenetics device provides significantly more traction than the standard Jes-Extender. Whereas the Jes-Extender can exert 1.5kg of traction on the penis, SizeGenetics has been upgraded to exert 2.3kg – making it one of the most powerful devices available.

Most of the studies into the effectiveness of penis extenders have used tension levels of only 1.2kg – 1.5kg. With the extra kilo of traction plus the faultless attachment system, the SizeGenetics extender can’t fail to provide better results than those achieved in clinical trials.

Faster Progress: The company throws in an extremely well structured DVD penile exercise program demonstrating a number of high intensity penile exercises to further stimulate growth.

One of the benefits of combining exercise with traction is that each method produces results through different physiological mechanisms: Traction through stretching, exercise primarily by increasing penile blood volume. By combining both you target the penis from every conceivable angle – which obviously promotes faster gains.

No risk purchase: SizeGenetics also provide a very good ‘results’ guarantee – in fact, the best of them all. To quality, you just need to use the device for 120 days – and if you’re not happy with the results, they’ll give you your money back. The other companies require you to use the device for substantially longer before they’ll offer you a refund.

Exclusive time-limited discount: If you’re quick, you can also pick up an additional $50 discount on the top of the line Ultimate Package – which brings the price down to $339.85. Check out the exclusive offer below.

Compare that to the $299 price tag for a Titanium Jes Extender bought without any accessories directly from DanaMedic, and that’s an amazingly well spent extra $40.

Free delivery is also included, which saves you a further $20 in comparison to the competition.

Jes Extender From SizeGenetics …

SizeGenetics Box ContentsSizeGenetics fully assembled next to boxSizeGenetics fully assembled - close up


Get An Exclusive $50 SizeGenetics Discount

SizeGenetics not only manufactures one of the most powerful and reliable medically certified penis extenders, they also provide one of the most comprehensive packages available – including the most flexible and user friendly attachment system, and a supplementary penile exercise DVD to turbo-charge progress.

Upgraded to 2300g tension and capable of penile lengthening up to 9.5 inches – the SizeGenetics Ultimate package provides absolutely everything to systematically and permanently enlarge your penis.

For a limited time, there’s also an extra $50 additional discount available – making SizeGenetics not only the most comprehensive package available, but by far the most competitively priced too.

To redeem this time limited offer, just enter the discount code WORLD50 on the checkout page of the Official SizeGenetics website.

Important: A lot of websites offer misleading or fraudulent promotional discounts to lure you into buying through ‘special’ links. Just do a search for ‘SizeGenetics Discount Codes’ in Google and you’ll see what I mean.

Search for these discount codes by all means, but make sure you don’t buy through their links when you find the ‘discounts’ aren’t legitimate. The truth is that SizeGenetics, like most well known brands, attracts a lot of frauds, fakes and imitators.

SizeGenetics only offer one legitimate discount code – WORLD50 – which gives a $50 discount. They even advertise this discount on their own site. There are no other discounts available.

So to avoid the bogus claims of the fraudsters, imitators and the false advertisers, make sure you only buy directly from the official SizeGenetics website using the only valid discount code available – WORLD50.

How all the Leading Devices Compare…

Penis Extender
Male Edge
Jes Extender
Pro Extender
SizeGenetics boxedMale EdgeJes-ExtenderPro Extender boxed
Traction Level / Power2.3kg
Significantly more powerful than standard Jes-Extender
Most powerful penis extender available
Standard power
Standard power
Ease of Use9 / 10
Reliable attachment / Precision Traction. Upgraded 58 piece comfort strap provides flawless comfort and secure attachment - even at maximum traction levels.
9 / 10
One piece design means no need to add or remove elongation bars. Secure attachment but the 58 piece SizeGenetics attachment package provides even better
7 / 10
Standard comfort strap - comfortable, moderately secure. Only 2 straps supplied though - letting the package down.
5 / 10
Uses standard silicone noose. Can be uncomfortable / reduce blood circulation / need regular reattachment.
Traction Precision9.5 / 10
Perfect calibration provides flawlessly maintained optimum traction levels. Not quite as simple to operate as Male Edge - but almost, and extremely reliable once set.
10 / 10
Innovative 'one-click' system not only provides extremely precise traction levels hour after hour, but is the easiest to adjust out of all the devices available.
8 / 10
Medical grade calibration. Reliable and precise - but requires more frequent readjustment than SizeGenetics and Male Edge/
8 / 10
Medical grade calibration - comparable to standard Jes-Extender.
Comfort9.5 / 10
58 piece attachment system not only provides extremely secure attachment, but also ensures that the device fits your penis perfectly (therefore as comfortably as a bespoke suit) too.
8.5 / 10
Comfort strap offers improved comfort over silicone noose. Ample extra padding also included to improve comfort and user experience.
7 / 10
Uses comfort strap design to reduce pressure on penile shaft but lacks the optional extras provided with SizeGenetics that can make all the difference.
4.5 / 10
Silicone noose can dig into the penis - causing soreness / numbness and restricted circulation to the penile head.
Results9 / 10
Provides the perfect balance of comfort / reliable traction / high power / secure attachment - offering unsurpassed ease of use and therefore, results.
8.5 / 10
The most powerful device / easy to use. Attachment not as secure as SizeGenetics however (particularly at higher traction levels) which can hinder progress.
7.5 / 10
Reliable / comfortable - the standard medical grade device providing approximately 1 inch growth for every 1000 hours wearing time. Calibration not as precise as Male Edge or SizeGenetics though and lack of additional attachment pieces means results take more persistence to achieve.
6 / 10
Precision calibrated, but severely let down by the reliability of attachment. Slips off frequently. That and standard traction power can lead to frustrating use and therefore limited gains.
Value8.5 / 10
The Ultimate package with every conceivable extra - 58 piece attachment system / upgraded high calibration tension / additional penile exercises to super-charge progress is good value at $399. With an extra time-limited $50 discount available (by entering discount code WORLD50 at checkout) SizeGenetics currently provides the best value 'complete' package available.
10 / 10
Starting at just $179, with the top of the range Pro device retailing for just $219 - Male Edge is the best value 'device only' extender money can buy. Manufactured by the same company that manufactures the SizeGenetics device - Male edge provides some extremely innovative features at a rock bottom price.
7 / 10
$499 for the standard device without extras or upgrades makes the original Jes Extender seem a bit pricy in comparison to SizeGenetics, which is the same device but with upgraded power and a host of additional spares and accessories.
7.5 / 10
A few extras - such as the inclusion of a penile exercise DVD - make this slightly better value than the standard Jes Extender - but at $429.95, not by much.
Overall9.5 / 10
It's hard to conceive how this package could be improved. A medical grade traction device / every conceivable extra to improve performance and ease of use (including upgraded power and better attachment system) make SizeGenetics the ultimate choice. Perfect if you're looking for an all-inclusive package that'll never need upgrading or parts replacing.
9 / 10
Simply offers amazing value for such a powerful, reliable device. Only downsides are the lack of attachment accessories / bonuses. But if these aren't important to you and you're looking for a 'device only' solution, Male Edge is the option to choose. No thrills power, reliability and ease of use at an astounding price.
7 / 10
Considering the stiff competition, the original Jes Extender is now over priced for what you get.
6 / 10
A medical grade traction device, but so let down by the silicone attachment method, that it's looking decidedly outdated when stacked up to the current competition.
Price:From $199From $179From $299From $349
Visit Official WebsitesOfficial SizeGenetics Site
Remember to enter the time-limited discount code WORLD50 at checkout to save another $50
Official Male Edge SiteOfficial Jes-Extender SiteOfficial Pro Extender Site

The Fundamental Facts About...