9mm Gen 2 Silent Captured Spring System Short Stroke Version - 9mm Gen2 Silent Capture Spring Short Stroke All Steel Mass

From Brownells.com

The 9mm Silent Captured Spring is a drop-in component that softens recoil and reduces cycling noise and vibration in your 9mm carbine. The result is a refined rifle that's a pleasure to shoot. Paired with our 9mm bolt assembly, you have the most reliable 9mm operating system available. The 9mm Short Stroke Version provides the same reliable buffering as our other 9mm SCS models but with a shorter overall stroke. Designed for competitors looking for every edge, this model offers snappier cycling with even less felt recoil thanks to the shorter stroke.