Custom hi capa 5.1 Dm for complete parts list. The entire upper has been redone. Built for rate of fire. Tracer not included. Includes primary airsoft m4 adapter Parts list quick summary: Threaded Outer barrel Tight bore inner Tapp slide Recoil spring Nozzle spring Brass Hop up New bucking Gas route replacement Short stroke cowcow Guarder blowback nozzle Masterpiece blowback housing