The Foxtrot Mike Products Complete .45 AR upper is the package you have been waiting for to finish your Glock mag AR-45 build. This .45 upper receiver comes with all the features you want in a pistol caliber carbine. It has a 16" barrel with a muzzle brake. Utilizing a monolithic design that indexes with the flat top upper receiver, this handguard is securely attached and won't rotate loose until you purposefully take it off. Included is a heavy .45 bolt designed to reliably cycle when used with carbine recoil springs. Keep your lower receiver from getting lonely with this FM Products .45 upper.Features: Designed for use with Glock Magazines 16" barrel with muzzle brake attached 15" M-LOK handguard Full length picatinny top rail Hardcoat anodized black finish Includes heavy .45 bolt Includes Mil-Spec charging handle Compatible with Mil-Spec lowers or dedicated .45 lowers