The Samson Evolution Series features a free-floating AR-15 rail system. Being lightweight and durable allows the Samson Evolution Series to offer the perfect upgrade for 3-Gun competition shooting, law enforcement and military personnel or weekend enthusiasts. Accessory picatinny rails can be added or removed at any of 7 positions around the rail and any place along the length of the tube. Rail accommodates most piston systems. KeyMod versions of the Evolution Series do not include accessory rails. This is the 7.6" Carbine Length Keymod Evolution Rail.