Let’s Define “Double Stack”
Cosaint Arms® developed the cosClutch™ grip kit to be used in conjunction with the classic 2011® double stack designed and made popular by STI in the 90s. It was modeled after the STI Gen I grip, and that designation makes a difference with the mag catch and possible magwell fitment. Many people use the term “double stack” to identify Glocks, Sigs, and Rock Island Armory’s wide-body 1911 platform. Those are all double stacks, but for our purposes here, we’re only referring to the classic STI version of the 2011® with separate grip and frame construction.
With so many new manufacturers building on this double stack design, the most frequent question we hear is: “Does it fit ____________?” This guide covers every supported platform as of current production, explains how the grip kit and tactical magwell fit differently, and tells you exactly how to verify fitment before you place an order.
What the cosClutch™ Grip Kit Includes
Before getting into compatibility, it helps to know what your grip kit includes. The Your Extra+Points™ cosClutch™ grip kit is a three-piece system: a machined aluminum grip, a machined aluminum mainspring housing (MSH), and a steel extended, drilled and tapped magazine release.
Supported Platforms
The cosClutch™ system currently supports 18+ double stack 1911/2011® platforms. Here’s the full list.
Staccato (STI)
- Staccato XL
- Staccato XC
- Staccato P
- Staccato C2
If you’re running an older STI-branded frame (pre-Staccato rebrand), see the verification notes below.
Cosaint Arms®
- Cosaint COS21 – Double Stacks
Springfield Armory
- Springfield Prodigy – Double Stacks
EAA / Girsan
- Girsan Witness2311
See the review by SmashTime: youtube.com/watch?v=Gs-53dEeNEI.
Bull Armory
- Bull Armory SAS II – Double Stacks
The Bull Armory frame is the most unique 2011-style frame on this list. It’s the only frame that has the grip bushings built as part of the frame itself, so some modifications are required for the grip to fit.
Also Supported (Double Stacks)
- Nighthawk Custom
- Kimber
- Atlas Gunworks
- Alpha Foxtrot Romulus
- Military Armament Corp (MAC)
- Taran Tactical
- Phoenix Trinity
- Bersa
- GP Arms
- Watchtower
- Live Free Armory
- Great Lakes Firearms & Ammunition
Others
The list above reflects confirmed, tested fitment. New manufacturers are developing all the time. If your pistol isn’t listed, see the section near the end of this guide.
Known Exceptions and Unsupported Models
A few categories to be aware of:
Single stack 1911 frames. The cosClutch™ system is designed exclusively for double stack 1911 frames. It will not fit a standard single-stack 1911, full stop. The grip width, MSH, and magazine release are all dimensioned for the wider double stack frame.
Staccato has a few models. The original single stack R and C, the newer CS and new C, and the most recent HD models do not work with the cosClutch™.
Heavily modified or custom frames. If your pistol has had significant frame work done — frame welding, an aftermarket grip already installed with modification — verify fitment directly. Custom work can change the tolerances the grip kit relies on.
How to Verify Fit
For any pistol on the confirmed list, here’s what to check:
- 1. Identify your exact model and variant. Manufacturer and model name.
- 2. Check the model year if relevant.
- 3. Look for frame modifications. If the gun has had grip work done by a smith, note it before ordering.
- 4. Contact Your Extra+Points™ directly. If you’re in any doubt, reach out through yourextrapoints.com before you order. We’d rather confirm fitment before the sale than have you dealing with a return.
Grip Kit Fit vs. Magwell Fit: Not the Same Question
The grip kit (aluminum grip + MSH + magazine release) and the tactical magwell are separate purchases that fit differently.
The tactical magwell attaches to the base of the grip using a fitment that’s compatible with STI Gen I grip designs. However, if your pistol has a factory-integrated magwell — some competition-oriented configurations ship this way — you’ll need to verify before adding a Your Extra+Points™ magwell.
The tactical cosAnchor™ magwell comes in four finishes. Matching it to your grip kit finish is purely aesthetic, but it’s worth thinking through at the time of purchase.
- Raw aluminum: $60 – shop raw
- Black anodized: $75 – shop black anodized
- Cerakote: $85 – shop Cerakote
- DLC: $100 – shop DLC
What to Do If Your Platform Isn’t Listed
The double stack 1911/2011® market keeps growing. Manufacturers such as Bull Armory and others produce double stack 1911/2011® pistols that are similar to, but different from, the original 2011® double stack.
If your platform isn’t on the list:
- Check the compatibility page at yourextrapoints.com for any updates since this guide was published.
- Contact YEP directly — if enough customers have the same platform, it often gets added to the confirmed list quickly.
- If you have a local gunsmith familiar with double stack 1911/2011® platforms, they can often assess frame compatibility on the bench in minutes.
We don’t want to oversell compatibility or undersell it. The machining tolerance on the cosClutch™ system is tight by design. That precision is what produces the feel people pay for, and it means fit has to be confirmed rather than assumed.
Ready to Order?
Start by visiting the product pages below and verify your platform.
cosClutch™ Aluminum Grips:
cosAnchor™ Tactical Magwells:
Still unsure whether your pistol is compatible? Reach out through yourextrapoints.com before you buy.