American Defense Mfg. AD-509T, Optic Mount, Lower 1/3 Height, Anodized Finish, Black, Quick Release, Fits Holosun 509T Footprint AD-509T-11-STD 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.