The FASTT AEMS positions HolosunT AEMST optics at a 2.26? Optical centerline from the rail. It comes standard with a two cross bolt rail clamp, but is compatible with the FASTTQD (Quick Detach) Lever. It can be paired with any FASTT FTC (Flip-to-Center) magnifier mount. FASTT is a series of optic mounting solutions that provides end users with a quicker sight picture than standard height mounts. FASTT mounts create a 2.26 optical centerline from the rail, which allows for more rapid visual processing of the field by ensuring an ergonomically correct heads-up posture. Further, they provide faster and easier dot/reticle acquisition while wearing night vision goggles, protective masks, and other gear. HEIGHT: 2.26? To Optical Centerline. COMPATIBILITY: HolosunT AEMST Optics. MOUNT TYPE: 2 Cross Bolt Rail Clamp. DIMENSIONS (W X L X H):IN. COATING: Type III Hardcoat Anodized.