The Nikko Stirling Mountmaster AO Match Mounts are made of highest grade aluminium with matte black finishing, accurate, reliable and designed for all categories of rifles. Available for 3/8” and weaver rails in low, medium and high for perfect fit of your 1” or 30mm scope. Four screws hold the upper part of the ring to the base which gives additional strength and ruggedness. This dovetail styled mounts feature across the series a recoil stop to minimize the impact of recoil. Always precise.