With your AR15 Upper & Carrier, this 7.62 X 39mm Caliber Windham Weaponry Barrel Kit gives you the conversion parts need to build up a 7.62 x 39mm Upper Rec. Assembly. It is 16″ in length in an M4 profile, and includes the Barrel Extension, Barrel Nut, Front Handguard Cap, a Mil Std 1913 Railed Sight Base with Sling Swivel, Bayonet Lug and a 7.62 x 39mm Bolt. Machined from 4150 Chrome Moly Vanadium 11595E Steel, this highly accurate barrel is Chrome Lined in both Bore and Chamber for long wear and ease of cleaning. A Black Manganese Phosphate finish offers protection against rust and corrosion. Rifling is 1 turn in 9.5 inches – right hand twist – with 4 lands & grooves for optimum accuracy with a wide range of 7.62 X 39mm ammunition. The muzzle is threaded 5/8″ x 24 T.P.I. to accept the supplied flash hider.