Lion Gears BridgeMount Extended Slim Low Profile Long Rails. Perfect to Mount Dot Sight with Magnifier Purpose. Low Profile 0.5" high, 10" long, 25 slots with 5 7/8" overhang, 80mm Mounting Slots Spacing. Rock Solid Design with Steel to Steel Locking Screw & Nuts; Not Those Bolted into Aluminum Where Trouble Bounded to Happen Sooner or Later!. Lightweight Slim Design at 4oz