Give a strong support to your optics or accessories with the aluminum Weaver Top Mount Base #12. It is compatible with Weaver rings and can serve as a front or rear base on select firearms.Front Base: H&R 800 Savage 6, 7 Winchester 74 Remington 514, 550 Stevens 57, 76, 4171/2, 762, 85, 87, 872 Marlin 80, 81, 900, 917, XT-22, XT-17 Mossberg 50, 51, 151, 152, 350, 352Rear Base: H&R 800 Sears 42, 43 Remington 514, 550 Savage 4, 5, 6, 7, 219 Marlin 80, 81, 900, 917, XT-22, XT-17 Winchester 57, 69, 69A, 72, 47, 74 Mossberg 25, 26, 42, 46M, 140, 142, 146 Stevens 56, 66, 57, 76, 4171/2, 762, 85, 87, 872 Mossberg 45-46 with 3/4" diameter barrels, 43, 44, 144, 46 BT, 35, 45, 46 Mossberg early models with 13/16" diameter barrels, 50, 51, 151, 152, 350, 352