Optional quick detach lever for the following FAST mounts: FAST Micro, FAST Micro-S, FAST Optic Riser (as of Aug. 2023), FAST Absolute Riser, FAST Comp Series, FAST MRO, FAST MRDS, FAST MicroPrism, FAST FTC OMNI, FAST FTC 30mm and FAST FTC PA magnifier mounts come with this lever pre-installed. NOT compatible with the FAST COG Series and FAST LPVO mounts. The UNITY proprietary nut is required to prevent damage to the mounting interface. Use of a standard ADM nut (not UNITY proprietary) will cause damage to the host rail and is not covered under warranty.