These See-Thru Top Mount Rings (49720) are made to mount to specific firearm receivers to enhance fit and performance. No bases are needed when using these rings. The perfect baseless system allows you the flexibility to shoot with open sight or scope on the same gun. Designed for scopes with 1" tubes. These rings let you choose between a quick iron sight shot or using the scope. For 1" scope tubes only. No base is required. This mount will position the scope about 7/8" above the receiver.