A high quality bolt is a must in any AR-15. Whether you need a spare bolt or are looking to upgrade an existing rifle, look no further. This is the same bolt we use in our builds.Mil Spec BoltFeatures: Phosphate and Nickel Boron Finish 158 Carpenter Steel Shot Peened High Pressure Tested (HPT) Magnetic Particle Inspected (MPI)Mil Spec Extractor: 8620 Tool Steel Phosphate and Nickel Boron Finish Extractor Spring Black Extractor Insert Viton O-Ring Weight: 1.53oz