Leupold Mark 4 Rings Picatinny 35mm Medium Black Matte These Rings Are machined From Solid Steel, They Offer Superior Integrity And tighter tolerances That Are based On The proven Cross-Slot Design. Use Leupold Mark 4 Bases, QRW/PRW Bases Or Any Other Picatinny-Style Mount Rails. Tube Diameter: 35mm Height: Medium Finish: Matte Style: 2 Piece Material: Aluminum Mount Type: Picatinny