Designed for AR-style rifles, our SPR (Special Purpose Rifle) mounts feature a specialized, sleek design to deliver optimal height with a forward cantilever for AR platform rifles. INTREGRAL RECOIL LUG BASE DESIGN FOR IMPROVED ACCURACY AND RETURN-TO-ZERO CAPABILITY. Optimal height and forward cantilever for AR-style rifles Integral recoil lug base design for improved accuracy and return-to-zero capability Mfg: Weaver