The IOR Tactical QD rings are very strong and very reliable. Unlike the cheaper copies on the market, our rings have steel crossbolts, and 4 T-15 torx screws each and will have no chance to slip or come loose on the base, or the scope tube to slide inside the ring. Levers are spring loaded to allow for 6 reindex positions. Height is 3/4 inch from the top of the base to the bottom of the ring. Will mount on any Weaver or 1913 Picatinny base.