FAST Riser securely elevates block-type red dot optics with a standard lower 1/3 cowitness picatinny mount to a 2.26a ^2 optical center line. FAST(TM) Riser provides an elevated M1913 Picatinny platform for direct attachment of optics such as EOTech EXPSA(R), Leupold LCOA(R), Vortex UH-1A(R), and other "lower 1/3" optics*. *Technically, the FAST(TM) Riser will support "absolute cowitness" optics such as EOTech XPSA(R), Sig Sauer Romeo8HA(R), etc. But, compatibility with the FAST(TM) FTC Magnifier Mount will be limited. The FAST(TM) Riser comes standard with a rail-grabber clamp. A Flip-Up Offset Backup Rear Iron Sight Mfg: Unity Tactical