Accu-Tac 30MM Scope Rings Flat Black Model HSR-300 Accu-Tac's Scope rings are Precision CNC machined to very tight tolerances on the height, center-line, and tube bed arch. For perfect alignment of the scope it utilizes a built in bubble level for perfect leveling of your rifle, and high strength hardware for durability. Type: Ring Set Tube Diameter: 30mm Height: 1.3" Size: Accepts up to 56mm Finish: Black Material: Aluminum One or Two Piece: Pair