Lion Gears BridgeMount Tactical Picatinny Cantilever .5" Riser, 3.73" Long with 9 Slots, System Oriented Design with Under The Rail Opening-Build a Flexible and Compact Mounting System, BM0905EX System Oriented Design with Under the Rail Opening-Build a Flexible and Compact Mounting System Robust and Light-Weighted Design with Steel-to-Steel Connection between Screw and Locking Nut Plate Precision Machined Solid Aircraft Grade Aluminum with Hard Anodizing for Tight Tolerance and Durability See-Thru Design with Picatinny/Weaver Mounting Base 9 Slots, .5" hight with 3.73" long