The Odin Works Low Mass Bolt Carrier Group is a High Performance part that will change the way your rifle feels and shoots. This BCG has been significantly lightened, weighing in at only 9 ounces, it dramatically changes the amount of mass reciprocating in your gun. This BCG also features a Salt Bath Nitride finish that is both slick and durable. The carrier is made from 8620 steel and the bolt from 9310 steel. Bolt Carrier Group fits AR15/M4 compatible style Rifles (i.e.) .223/5.56mm, .300 Blackout.Note: This is a HP or High Performance part. It will change how your rifle feels and shoots. Tuning may be required to make the gun properly run with this part. This can be done via the gas system or the buffer system.