This is what everyone has been waiting for! 20+ fpe gain!! Makes your rifle very powerful without over working the gun. Highest quality materials used. Porting and mill work is done to the valve and housing, heavier hammer weight, delrin C3 and larger external regulator plenum. Rifles must be sent to SPAW for kit installation, kits can not be purchased and shipped uninstalled. Perfect for slug users! Cost does not include return shipping.