Warnex 40mm Mounts XSKEL34TW Warnex 40mm Mounts, Gen 2 Extended Skeletonized Msrx 40mm Mount Picatinny-Style with Rings, 1Piece, 34mm Tube Diameter, Matte Black Lightweight, skeletonized aluminum body and caps to reduce overall weight without sacrificing reliability 8 Torx style fasteners with steel threaded inserts to prevent stripping Additional 1 inch cantilever forward design to provide additional Eye relief