Leupold Mark 4 Tactical rings are the lightest weight of all the Leupold mounting systems. Built from aircraft grade aluminum these machined rings offer excellent integrity and tighter tolerances that are based on the proven cross-slot design. The 1/2" keeper nuts are designed to lock the rings solidly against Leupold Mark 4 base, PRW, or any other picatinny style mount. If lightweight yet extremely durable rings are your primary concerns trust Leupold Mark 4 rings to satisfy the matter. Features and Specifications: Manufacturer Number: 57398 Leupold Mark 4 Tactical Scope Rings 30mm Tube Diameter Medium Height .2405" Measured from base of ring to bottom of scope tube Aircraft Grade Aluminum Construction Matte Black.