I have a geissele 11.5 build everything on it is geissele accept the barrel,bolt and trigger. The barrel is FN 4150V Chrome Moly vanadium steel, phosphate coated and chambered in 5.56NATO with a 1in7" twist.Bolt made of mil-specshot- peened Carpenter 158 steel.it will come with everything you see and it has never been shot if you need more info please contact me at 936-224-9523 must be willing to sign bill and be 21 or older with valid Drivers license or LTC