Features: This 3.7" long Picatinny/ MIL-STD 1913 rail mount replaces the factory rear sight base and allows the mounting of optics directly to PC Carbine barrel. This rail mount bolts directly to the barrel rear sight base and the factory windage and elevation iron rear sight bolts onto the rear of the mount. Picatinny rail has 8 slots for flexible mounting of Picatinny/ weaver type scope rings. Picatinny rail is 3.7" long. Overall length: 5.0" U.S. PAT. D888541