This kit includes a wide-variety of components to complete your AR-15 build. The upper receiver comes fully assembled with a 16â€ chromoly barrel chambered in 5.56 and with an A2 flash hider. A 12â€ MLOK rail allows attachment of various accessories. The mid-length gas system is non-adjustable. Also includes a Spec15 charging handle, MFT Minimalist stock and MFT Engage Series grip. The lower parts kit includes a buffer tube, castle nut, end plate, carbine buffer spring with a 3 oz carbine buffer, complete firing assembly, roll pin, spring, detent kit, trigger guard, bolt catch, selector, mag catch, pivot and takedown pins. This kit has everything needed to complete your build, minus the lower receiver and bolt carrier group.