The FAST Micro-S is specifically designed for the Aimpoint CompM5s, CompM5b and Duty RDS mini red dot sights.It puts these taller " micro" sights at the established FAST height of 2.26" and is fully compatible with the entire line of FAST magnifier mounts. It comes standard with a two cross bolt rail clamp, but is compatible with the FAST QD Lever. It can be paired with any FAST FTC magnifier mount. Features2.26" Height to Optical Centerline