Leupold RM Sako 1-in Medium MatteUse as a high-quality alternative to ringmounts sold by firearms manufacturers and as a no-tap mounting method for most .22 rimfire rifles with an 11mm, 13mm, or 3/8" dovetail rail. Superior integrity and tighter tolerances because we machine them from solid stock.Ring Diameter (in): 0.86Height (in): 1.00Ring Diameter (mm):25.40