Weaver Detachable Top-Mount Base Browning/Mauser/Winchester Standard Mount No. 46 Black

Nobody makes bases to fit as many guns as Weaver. Yet each base is machined to tight tolerances for a custom fit. They're designed to fight the effects of recoil with a square cut notch that precisely mates to the sturdy cross bolt in every Weaver Detachable Ring. Custom hardened fastening screws come with every Weaver base.
No.46 mount