The Kaw Valley Precision Plan B Brake is seamlessly engineered to be fully compatible with Plan B mounting systems. Designed to effortlessly attach and detach from your firearm, our brake ensures quick and hassle-free adjustments to your shooting setup without the need for timing or shims.Features: 17-4 Stainless Steel Material Black Nitride QPQ Finish OAL: 1.27 Bore: .500" (ANY Caliber) Weight:1.7oz Shoulder: Square