We are officially licensed and approved by Dead Air Silencers to incorporate their KeyMo mount design with our muzzle device designs. The KeyMo FG42 is compatible with Dead Air's KeyMo-equipped silencers. FEATURES In-house heat treated to condition H900 for a through-hardness of 45-47 HRC 17-4 stainless steel that is heat treated to condition H900 exhibits 14% higher ultimate tensile strength over hardened 4140 steel Shim kit included