Knight's Armament URX (SR-15 Carbine). Rail is approximately 7 3/16" long. Free floats the barrel, bottom rail is removable. Picatinny rails on all four sides allow endless possible mounting solutions for accessories such as sling mounts, vertical forearm grips, flashlights and more. This Knight's Armament URX handguard has four QD sling swivel sockets (2 on the left side, 2 on the right side). Two front sockets are only usable with the bottom rail removed. The URX comes with three 11 rib panels to help protect the rails from damage.