Designed exclusively for the Aimpoint Comp. ML 1" ML 2 and ML 3 sights. Low standard height allows perfect Red Dot co-witnessing on M16/M4 with A.R.M.S. #38 Swan Sleeves and S.I.R. Systems without a spacer. A full spacer is required if mounting directly on the flat top rail. The #17 Mt. is included in the purchase of this #22M68 Mount.