Weaver one-piece aluminum base is machined to tight tolerances for a custom fit. Base offers maximum strength for rings to hold tight and cross-lock design to fit a variety of rings. Fits- Henry 30/30, 45/70 Big Boy; Marlin 45, 30AS, 336, 444, 1893, 1894, 1895, Camp9, 922M, 989, 22 Auto; Mossberg 640; Western Field 740.