The MPX PSB(TM) is an innovative, 3-position adjustable Pistol Stabilizing BraceA(R) 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. FEATURES 3-postion adjustable Dual compatible with SIG MPX and SIG MCX (excluding SIG MPX Copperhead) Complete assembly, ready-to-install, with an integral M1913 adjustable housing US veteran designed and proudly made in the USA PRODUCT INCLUDES: Complete assembly Mfg: Sb Tactical