This 90mm Gun Star Weaver adapter/base features recoil resistance, heat treated steel with a blued finish, and is guaranteed to return to zero after remount. This base has a very low mount, 6 weaver and 1 picatinny recoil grooves, and is compatible with all firearms with a Blaser R93, R8, LRS2, K95, or S2 saddle mount system. Gun Star® We take pride in precision Gun Star 90mm Weaver adapter/base for Blaser GS-Blaser-5