The American Defense AD-B3 Modular Base is the second largest base in the American Defense modular lineup. Standalone it is a full-size ACOG mount. Alternatively it can accept several different risers to accommodate a variety of uses. It is precision machined from 6061 T6 aluminum and finished in hard coat T3 Mil-Spec anodize. It features the patent pending Auto Lock Lever system to accommodate both in spec and out of spec rail systems. The Auto Lock Lever system has the following advantages: Notes:Does not require proprietary tools for adjustmentCan be adjusted with your finger or a flat blade screwdriverLever can be configured to lock to the front or the rearSuperior clamping surface to insure maximum rail engagement