SB Tactical MPX PSB Sig MPX/Sig MCX 3 Position Adjustable Pistol Stabilizing Brace - Black - The MPX PSB is an innovative, 3-position adjustable Pistol Stabilizing Brace dimensioned to fit the receiver cuts of the Sig Sauer SIG MPX and SIG MCX. Ships as a complete assembly, ready-to-install, including an M1913 receiver saddle. MCX Installation: Not compatible with the SIG MCX Stock Adapter Kit. You must have a genuine SIG MCX Lower Receiver for compatibility. Note - This does not fit some models of SIG MPX Copperhead. US veteran designed and proudly made in the USA 3-postion adjustable Dual compatible: SIG MPX and SIG MCX (excluding SIG MPX Copperhead) Complete assembly, ready-to-install, with an integral M1913 adjustable housing Product Includes: Complete assembly Adjustable nylon strap