The AD-B3 modular base is a mount for for the full sized 3x Power ACOG scopes, such as the TA01, TA11 and TA31. Also fits scopes with similar ACOG Style Bases such as the Burris AR-332 and newer model Trijicon RX-30 optics with 3 inline mounting holes. The overall length of the base is 3.5". It is precision machined from 6061 T6 aluminum and finished in hard coat T3 Mil-Spec anodize. It features the Patented QD Auto Lock Lever system to accommodate both in spec and out of spec rail systems. ADM AD-B3 Tac Lever Modular Base