Extra wide oval opening below the scope allows fast, unrestricted use of iron sights when you're too close to use a scope. All steel, four screw top strap gives 210Adeg surface contact for recoil-proof strength. Integral aluminum base means lighter weight. Mfg: Weaver SPECS: 1" (2.5cm) I.D. Overall height approximately 2" (5.1cm). 3 oz. (85g) per pair. Aluminum lower half, steel cap and screws. Satin blue finish.