This one-piece aluminum base is machined to tight tolerances for a custom fit. It offers maximum strength for rings to hold tight. Screws are included. Fits Anschutz 1568; Browning Bolt Action BBR, HI-Power, other caliber (older mod); Churchill 950, 950C, 972C; Colt 57; Cooey 71; Enfield w/receiver cut down like Win 70; H&R 300, 301, 330 & 370 (pre 1973); Marlin 455, MR7; Mauser; Ruger American; Savage A17, Axis, Series, Edge; Win 52.