The tekko metal ar carbine integrated rail system is a drop in screw less installation, the unit is held in place by the delta ring and handgaurd cap.The four mil-std 1913 picatinny rails provide a secure platform for mounting.A monolithic style continuous top rail eliminates the gap between the receiver and rail.The lightweight aluminum construction is a hard coat anodized.Type: AR Rail SystemFirearm Type: AR RifleFirearm Model: AR-15/M16/M4Material: AluminumFinish: BlackFeatures: Picatinny Rail