The FAST Absolute Riser is designed to raise your block-type red dot optic, like the EOTech XPS or Leupold LCO, to a 2.26" optical centerline. This provides an elevated M1913 Picatinny platform for a direct and secure attachment, ensuring an absolute co-witness.For enhanced versatility, the FAST Absolute Riser seamlessly pairs with any FAST FTC (Flip-to-Center) magnifier mount. It comes standard with a two-cross bolt rail clamp but is also compatible with the FAST QD (Quick Detach) Lever for quick and easy attachment and removal.