The utg pro model 4/ar-15 carbine length drop-in quad rail offers easy installation with no modification to the barrel.The top/bottom two-piece design has integral spinal cords/alignment housing for a perfect fit with the barrel nut and round front cap.It is precision cnc-machined from from aircraft aluminum with anodizing/engraving.The four picatinny rails each have 14 slots with great zero-retention capability for all installed accessories.This quad rail system is designed to fit carbine-length model 4/15 with a standard ar15 gas tube.It includes black rubber rail guards and has a black anodized metal finish.Note-this quad rail system is designed to fit with standard ar-15 gas tube.The compatibility with any special piston system is not guaranteed.Made in the usa.Rails: PicatinnyType: Railed HandguardFirearm Type: CarbineFirearm Model: AR-15Material: AluminumFinish: AnodizedFeatures: 14 Sections Per RailPositions: 4