These SEE-THRU rings are made to mount to specific firearm receivers to enhance fit and performance. No bases are needed when using these rings. Mounts have steel straps for added strength. Lower ring and base are one piece. Steel-strap top design for increased hold. Size 1" Ring Type 2-Piece Base/Rings Style See-Thru/Lock Ring Finish Black Height Lock Ring Series Scope Mount/Ring Combo Material Aluminum Mount Type To Receiver Tube Diameter 1" One Or Two Piece To Receiver Style Description Rifle