This m4 carbine-length, drop-in quad rail by aim sports is an easy to install upgrade for the basic carbine.Made from aircraft-grade aluminum, it is compatible with most carbine-length direct impingement gas systems.The two-piece design requires no gunsmithing to install and is compatible with all standard weaver/picatinny 1913 accessories.Rails: 4 PicatinnyType: Quad RailFirearm Type: CarbineFirearm Model: AR15/M16/M4Material: AluminumFinish: Black Hardcoat AnodizedFeatures: Easy Installation