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.Type: 2-Piece Base/RingsTube Diameter: 1"Height: Lock RingSize: 1" RingFinish: GlossStyle: See-Thru/Lock RingMaterial: AluminumOne Or Two Piece: To ReceiverMount Type: To Receiver