The KAC 5.56 MAMS (Multi-Axis Muzzle Stability) Brake has been engineered to increase controllability, to significantly reduce felt recoil, and to help mitigate a rifle's flash signature as compared to traditional muzzle brake designs. The MAMS is a neutral bias brake that combats both muzzle rise and drift upon firing. Depending on the gun's barrel length, it can reduce felt recoil in a 5.56 x 45mm gun by as much as 67 percent. The 5.56 M4QD NT-4 MAMS is compatible with KAC's QDSS-NT4 5.56mm sound suppressor, and comes complete with a 7-piece shim kit and installation instructions. Specifications:Weight: 2.3oz (65g)Length: 1.88a ^2 (46mm)Thread Size: 1/2a ^2 x 28Suppressor Compatibility: KAC 5.56 QDSS-NT4