Mentor GFS™
The Mentor GFS was a two-piece inflatable penile prosthesis introduced in 1988 for the surgical treatment of severe erectile dysfunction. Its defining feature was the elimination of the separate abdominal reservoir: the pump and fluid reservoir were combined into a single scrotal unit known as a resipump, connected by tubing to two inflatable penile cylinders. A revised version, the GFS Mark II, removed the tubing connectors to improve reliability. Neither model is manufactured today. This page is intended primarily for men who already have a Mentor GFS or Mark II implanted and are considering revision, replacement or conversion to a modern device.
- Discontinued device — The Mentor GFS and GFS Mark II are no longer manufactured or supplied. Any GFS still in a patient today is a device implanted decades ago.
- Two-piece, not malleable and not three-piece — Paired cylinders were linked by tubing to a combined reservoir-and-pump unit implanted in the scrotum.
- The resipump was the core idea — Combining the usual intra-abdominal reservoir and the scrotal pump into a single scrotal unit was the device's central simplification.
- GFS stands for girth, flaccidity and simplicity — The acronym reflects the three design goals set for the device.
- Mark II removed the connectors — The second-generation Mark II eliminated the need for tubing connectors.
- Mixed historical reliability — Published studies reported around 86% satisfaction alongside mechanical malfunction rates of 14–32%.
- Superseded by modern platforms — Men needing a two-piece today are offered the Ambicor; men wanting maximum rigidity and flaccidity are offered a three-piece such as the Titan or AMS 700.
About the Mentor GFS™
What Was the Mentor GFS Penile Implant?
The Mentor GFS was an inflatable penile prosthesis manufactured by Mentor Corporation.
It was designed for men with severe erectile dysfunction who were candidates for penile implant surgery.
It was developed in the late 1980s by Dr Richard Fein in partnership with Mentor Corporation as a two-piece hydraulic implant.
The name is an acronym for girth, flaccidity and simplicity.
Those three words describe exactly what the design was trying to achieve: enough girth expansion to feel natural, enough flaccidity to conceal, and a simpler operation than a three-piece system.
Why the Device No Longer Exists
The Mentor GFS is not available anywhere in the world today.
The GFS and Mark II were withdrawn, with higher complication rates and poor reliability cited as the presumed reason.
Over the years a number of unitary and two-piece inflatables entered and then left the American market, including the Uniflate, Flexiflate, Mark II and GFS, leaving only the Ambicor.
Contemporary reviews describe the Mentor GFS as a now-defunct device.
If you are reading this because a surgeon mentioned the GFS, it is almost certainly in the context of a device implanted many years ago that now requires assessment.
What Happened to Mentor Corporation
Mentor no longer makes penile implants.
Coloplast completed its acquisition of Mentor's urology business in June 2006, and this purchase is what allowed Coloplast to expand into men's urologic health.
The Mentor inflatable line that survived that transition became the Coloplast Titan.
The GFS did not survive it.
The Two-Piece Concept
A two-piece inflatable penile prosthesis sits between a malleable implant and a three-piece hydraulic implant.
A malleable implant has no fluid at all.
A three-piece implant has cylinders, a scrotal pump and a separate abdominal or pelvic reservoir.
A two-piece implant keeps the hydraulics but removes the separate reservoir.
The trade-off is fluid volume: less stored fluid means less girth expansion and less true flaccidity than a three-piece device can achieve.
The Resipump
The single most distinctive component of the Mentor GFS was the resipump.
The GFS consisted of paired cylinders connected by tubing to a reservoir and pump combined into a resipump placed in the scrotum.
This removed the need to place a reservoir in the abdomen or pelvis.
For the surgeon, that meant a shorter and anatomically simpler operation.
For the patient, it removed an entire class of reservoir-related complications.
Fluid Adjustment as an Office Procedure
An unusual feature of the resipump design was post-operative adjustability.
In one series of 138 patients, thirteen required an addition of normal saline through the resipump as an office procedure.
An earlier Mark II series similarly reported four patients requiring post-operative addition of fluid to the reservoir pump.
This was presented at the time as a practical advantage over sealed systems.
It also indicates that the system's fluid volume was tight enough that some patients needed topping up.
Cylinder Design and Girth
The GFS cylinders expanded to a predetermined girth and were supplied in two different widths.
Expansion was therefore fixed rather than progressive.
This is a meaningful difference from modern controlled-expansion cylinders, which are engineered to expand in a defined way under hydraulic pressure.
Girth outcomes with the GFS were constrained by the limited fluid held in the resipump.
How Patients Operated the Device
The patient squeezed the scrotal resipump to move fluid into the penile cylinders.
The penis became rigid.
A release mechanism returned fluid from the cylinders back into the resipump.
The penis then returned toward a flaccid state.
Unlike a malleable implant, the GFS did not remain rigid between uses.
Unlike a three-piece implant, its deflated state was not fully soft, because a residual volume of fluid remained within the cylinders at all times.
GFS Versus GFS Mark II
The original GFS used tubing connectors to join components.
Connectors are a known weak point in any hydraulic prosthesis.
The Mark II was introduced as the next iteration and removed the need for tubing connectors.
This second-generation model was specifically intended to improve reliability and reduce complications after the original faced mechanical reliability issues and infections.
If a patient's operative record simply says "Mentor two-piece," the distinction between GFS and Mark II matters, because the connectorless Mark II performed considerably better in published series.
Early Clinical Experience
The original description of the device reported results from 56 successive implants and compared infrapubic and scrotal operative approaches.
That report concluded the device performed well and represented a useful addition to the range of penile implants available.
This was early, single-group, pre-modern-methodology evidence.
It should be read as historical context rather than as reliability data comparable to what modern devices are held to.
Mark II Outcomes
One Mark II series followed 80 men for up to 27 months, with six requiring repositioning of the reservoir pump.
A larger series of 138 patients implanted between October 1988 and December 1991, followed for twelve to fifty months with a mean of 31.7 months, reported a single mechanical problem involving the tubing.
Seven patients in that series required explantation, two of them because of post-operative infection.
Ninety-three percent of patients and ninety-eight percent of partners reported satisfaction with the prosthesis.
These are favourable numbers for the era.
They come from the device's own developer and from a small number of centres, which limits how far they can be generalised.
The Wider Reliability Picture
The picture across the broader literature is less flattering than the developer series alone.
Across limited published studies, patients implanted with the device reported a satisfaction rate of 86%, while mechanical malfunctions were reported in 14% to 32% of patients.
A malfunction rate in that range is far above what is expected from a modern three-piece prosthesis.
This gap between reported satisfaction and reported malfunction is the central tension in the GFS record, and it is the honest reason the device left the market.
Resipump Repositioning
Scrotal component migration was a recurring theme.
Six patients in one Mark II series required repositioning of the reservoir pump.
A combined reservoir-and-pump unit is necessarily bulkier than a pump alone.
That extra bulk in the scrotum is the direct cost of removing the abdominal reservoir.
Modern two-piece design has kept the no-reservoir principle while reducing scrotal component size.
Infection
Infection is a risk with every penile prosthesis.
Two of 138 patients in the Mark II series developed post-operative infection requiring explantation.
The GFS predates the antibiotic and hydrophilic surface coatings that are now standard.
Modern devices carry either an impregnated antibiotic surface or a hydrophilic coating that absorbs a surgeon-selected solution, and infection rates in contemporary series are substantially lower as a result.
Mentor GFS vs Ambicor
The Ambicor is the direct conceptual descendant of this class of implant.
AMS developed the Ambicor in 1994 as a similar self-contained pair of cylinders with a preconnected pump.
The Ambicor improved on earlier designs by using a separate scrotal pump to inflate the cylinders without needing a reservoir inside the penile anatomy.
Among the unitary and two-piece inflatables, the Ambicor is the only survivor, though it holds only a small share of the market.
For a patient today who specifically wants a two-piece device, the Ambicor is the option — not the GFS.
Mentor GFS vs Three-Piece Implants
A three-piece implant separates the reservoir from the pump and places it in the abdomen or pelvis.
That larger reservoir holds substantially more fluid.
More fluid means greater girth expansion when inflated and a genuinely soft penis when deflated.
None of the unitary or two-piece inflatables matched the three-piece in rigidity or flaccidity.
Devices delivering the best rigidity and flaccidity — the three-piece inflatables — grew in popularity and took the largest market share, while those performing less well on these two qualities sold poorly or were discontinued.
This is the clearest single explanation for why the GFS disappeared.
Mentor GFS vs the Coloplast Titan
The Titan is the modern Coloplast three-piece implant and shares corporate lineage with the GFS through the Mentor acquisition.
The Titan was introduced in 2002 and consists of two cylinders, a reservoir and a pump.
It offers full inflation and deflation, hydrophilic surface coating and current warranty support.
A GFS patient considering replacement is most often offered a Titan or an AMS 700, depending on surgeon preference and anatomy.
Mentor GFS vs Malleable Implants
A malleable implant contains no fluid and cannot fail hydraulically.
The Coloplast Genesis was introduced in 2004 with a hydrophilic coating, and it is trimmable and can be lengthened with rear-tip extenders while allowing the surgeon to prepare it with their own choice of antibiotics.
For a former GFS patient with scarred corpora, a malleable device is sometimes the more realistic replacement.
Device choice at revision depends far more on corporal condition than on what was originally implanted.
If You Already Have a Mentor GFS
This is the situation most readers of this page are actually in.
A GFS implanted in, for example, 1992 is now more than three decades old.
The device is out of production, so no replacement parts, cylinders or resipumps exist.
No manufacturer warranty is in force.
If the implant still works and causes no symptoms, there is no automatic requirement to remove it.
If it has failed, become painful, will not inflate or deflate, or shows any sign of erosion or infection, it needs urological assessment.
Revision and Replacement Surgery
Replacing a decades-old prosthesis is not the same operation as a first implant.
Scar tissue forms around implanted cylinders over time and can restrict corporal space.
Removal of an old device and placement of a new one is usually performed in a single operation where tissue conditions allow.
Corporal dilation, scar excision or downsizing to narrower cylinders may be required.
Where fibrosis is severe, a malleable implant may be the only device that can be safely placed.
Explantation Without Replacement
Some men choose removal without a new implant.
This should be understood clearly: erectile function does not return after explantation.
Removing cylinders from scarred corpora typically results in shortening and permanent loss of erection.
Where an implant is removed for infection, delayed reimplantation is generally more difficult than immediate exchange.
This decision deserves an unhurried conversation with an implant surgeon.
Does the GFS Restore a Natural Erection?
No.
Like all penile prostheses, it produced mechanical rigidity.
It did not restore arterial inflow, veno-occlusion or cavernous nerve function.
It also did not affect libido, sensation, orgasm or ejaculation, which depend on nerves and hormones rather than on the erectile mechanism.
Does the GFS Increase Penile Size?
No.
The cylinders expanded to a predetermined girth and came in two widths.
Girth expansion was limited by resipump fluid volume and was generally less than a three-piece device achieves.
No penile prosthesis is a lengthening device.
MRI and the Mentor GFS
Flag for verification before publishing. No current manufacturer MRI conditions statement could be located for the Mentor GFS or GFS Mark II, which is expected given that the device is discontinued and its manufacturer no longer exists as a separate company.
Recommended page wording: patients with a Mentor GFS should inform radiology staff of their implant before any MRI scan, and the radiologist should assess the device individually rather than relying on a manufacturer condition sheet.
Do not state or imply that the device is MR Conditional or MR Safe without a verified source.
Regulatory Status
Flag for verification before publishing. The Mentor GFS was marketed in the United States from 1988, but no active FDA clearance or approval number could be verified for a currently marketed version, and the device is no longer supplied.
Recommended page wording: the Mentor GFS is not currently approved or supplied in any market, and men seeking a penile implant today will be offered a currently regulated device.
Warranty
There is no warranty.
Mentor Corporation's urology business no longer exists as a separate entity, the device is discontinued, and no manufacturer replacement programme applies.
Any surgery involving an existing GFS is treated as revision surgery and priced accordingly.
Why This Page Exists
The Mentor GFS is not a treatment option for anyone choosing an implant today.
It matters for two reasons.
First, thousands of men still carry one, and they need accurate information when it fails.
Second, its design directly shaped the modern two-piece implant, and understanding why it was withdrawn explains why three-piece devices dominate today.
Is this device for you?
- •Men who already have a Mentor GFS or Mark II implanted and want to understand what they are carrying.
- •Men whose old implant has failed and who are considering revision or replacement.
- •Men told they have "an old Mentor two-piece" and want to know which device that means.
- •Patients researching implant history before choosing between a modern two-piece and three-piece device.
- •Clinicians and students studying the evolution of inflatable penile prosthesis design.
- •Not available — The device cannot be selected by any patient today.
- •No parts, no warranty, no manufacturer support — Failure means revision surgery, not repair.
- •Limited girth expansion — Resipump fluid volume constrained inflation compared with three-piece systems.
- •Incomplete flaccidity — Two-piece and unitary inflatables did not match the three-piece in either rigidity or flaccidity.
- •Bulkier scrotal component — Resipump repositioning was required in some patients.
- •High historical malfunction rate — 14–32% in published series.
- •No antimicrobial surface — Predates antibiotic-impregnated and hydrophilic coatings.
- •Revision complexity increases with time — Decades of corporal scarring make exchange harder than a primary implant.
How it compares
Every 2-piece inflatable implant a surgeon in our network may propose, side by side. The Mentor GFS™ column is highlighted.
| Attribute | Mentor GFS™Mentor CorporationEconomy | Mentor Mark IIMentor CorporationEconomy | AMS Ambicor™Boston ScientificPremium | Uniflate 1000®Surgitek, Inc.Economy |
|---|---|---|---|---|
| Expansion | Fixed predetermined girth; two cylinder widths supplied | Fixed predetermined girth; two cylinder widths suppliedFixed predetermined girth; two cylinder widths supplied | Primarily girth / rigidity; not a dedicated length-expanding cylinder | Dual-chamber cylinders — inner chamber for rigidity, outer chamber adding girth |
| Rigidity | Hydraulic, on demand; lower than a three-piece system due to limited fluid volume | Hydraulic, on demand; constrained by 25 mL fluid volume and prone to decline over years | Hydraulic inflatable rigidity | Hydraulic, on demand; constrained by scrotal resipump volume |
| Antibiotic coating | None — predates both InhibiZone and hydrophilic coating technology | None — predates both InhibiZone and hydrophilic coating technology | Do not publish a fixed antimicrobial-coating claim without verifying the current model-specific product documentation | None — predates both InhibiZone and hydrophilic coating technology |
| Reservoir | None separate; reservoir combined with pump into a scrotal resipump | None separate; 25 mL scrotal resipump serves as both pump and reservoir | Integrated within proximal cylinder system; no separate abdominal reservoir | None separate; scrotal resipump serves as both pump and reservoir, with a self-sealing penetrable fill port |
| Control | Manual — squeeze the scrotal resipump to inflate, release mechanism to deflate | Manual — squeeze the scrotal resipump to inflate, release mechanism to deflate | Scrotal pump; bend-to-deflate mechanism | Manual — squeeze the scrotal resipump to inflate, release mechanism to deflate |
| Concealed when soft | Partially — residual cylinder fluid prevents true flaccidity | Partially — residual cylinder fluid prevents true flaccidity | Yes, although generally less completely flaccid than many 3-piece implants | Partially — residual cylinder fluid prevents true flaccidity |
| Cylinder material | Silicone inflatable cylinders with connecting tubing (Mark II connectorless) | Silicone inflatable cylinders, connectorless tubing | Silicone elastomer construction | Two-layer construction: outer silicone layer, inner Dacron layer |
| Cylinder options | Two widths; length options historical and not currently documented by any active manufacturer | Two width sizes; length options historical and not documented by any active manufacturer | 12.5 mm, 14 mm and 15.5 mm diameters; 14–22 cm lengths depending on diameter | Supplied preassembled and prefilled with a trimmable tail; size range not documented by any active manufacturer |
| Length expansion | None — girth-expanding design only | None — girth-expanding design only | No dedicated longitudinal-expansion design | None — proximal length adjusted by trimming, not by expansion |
| MRI status | Not verified — no current manufacturer statement available; individual radiological assessment required | Not verified — no current manufacturer statement available; individual radiological assessment required | MR Conditional at specified 1.5T and 3.0T conditions | Not verified — no manufacturer statement exists; individual radiological assessment required, and the Dacron cylinder layer should be declared |
| Reliability | 90–95% at 5 yrs* | 90–95% at 5 yrs* | 90–95% at 5 yrs* | 90–95% at 5 yrs* |
*Type-level five-year mechanical survival from published series; not a model-specific figure. See each model page for detail.
At a glance
- Manufacturer
- Mentor Corporation
- Type
- 2-piece inflatable implant
- Price tier
- Economy
- Warranty
- The Mentor GFS is a discontinued device with no active manufacturer warranty, replacement programme or spare parts. Mentor Corporation's urology business was acquired by Coloplast in 2006 and the GFS line was not continued. Men with an existing GFS who require device removal or exchange are treated under standard revision penile prosthesis surgery pathways, and all costs are quoted as revision surgery.
- Two-piece inflatable design — Paired cylinders plus a single combined scrotal unit; no abdominal or pelvic reservoir.
- Resipump — Combined the intra-abdominal reservoir and the scrotal pump into one scrotal component.
- Fixed-girth expansion — Cylinders expanded to a predetermined girth and were available in two widths.
- Office-adjustable fluid volume — Saline could be added through the resipump as an office procedure.
- Connectorless Mark II revision — The Mark II removed the need for tubing connectors.
- No surface antibiotic or hydrophilic coating — Predates both technologies.
- Discontinued — Not manufactured, not supplied, no parts, no warranty.
Surgeons who implant it
Surgeons in our network who work with the Mentor GFS™. Availability of a specific model is always confirmed in your proposal.
Common questions
Can I still get a Mentor GFS penile implant?
What does GFS stand for?
What kind of implant was the Mentor GFS?
What is a resipump?
When was the Mentor GFS introduced?
What was the difference between the GFS and the GFS Mark II?
Why was the Mentor GFS discontinued?
Who makes the Mentor GFS now?
How reliable was the Mentor GFS?
What did the Mark II studies show?
My implant is over 25 years old. Does it need to come out?
Can a Mentor GFS be repaired?
What would replace a Mentor GFS today?
Is revision surgery harder than the first implant?
What happens if I have it removed without replacement?
Can I have an MRI with a Mentor GFS?
Is there any warranty on my Mentor GFS?
How is the GFS different from the Ambicor?
Why do three-piece implants dominate today?
Patient reviews
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- Chung — Penile prosthesis implant: scientific advances and technological innovations over the last four decades
- Patel et al. — Recent technological development of penile prosthesis: a literature review
- Polchert et al. — Narrative review of penile prosthetic implant technology and surgical results
- Fein — Mentor GFS inflatable prosthesis (PubMed)
- Fein — The G.F.S. Mark II Inflatable Penile Prosthesis (J Urol)
- GFS Mark II inflatable penile prosthesis — 138-patient series
- Ambicor Two-Piece Inflatable Penile Prosthesis: Background and Contemporary Outcomes
- Celebrating 50 years of penile implants — International Journal of Impotence Research
- The last survivor of unitary and two-piece inflatables — the Ambicor
- A history of penile implants — PMC
- Update on penile prosthesis — PMC
- Mentor Corporation — product information