The AD-509T QD mount was developed for the Holosun 509T red dot for use on AR pistols and other weapon platforms requiring a small, light weight red dot system. The AD-509T QD mount is a one piece unit 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. Features : The AD-509T QD mount features the Patented QD Auto Lock Lever system. Does not require proprietary tools for adjustment. Can be adjusted with your finger or a flat blade screwdriver. Lever can be configured to lock to the front or the rear. Superior clamping surface to insure maximum rail engagement.