This 8 position AR-15 Buffer Tube Kit is machined from industry-standard 6061-T6 aluminum with a MIL-A-8625 Type III, Class 2 hard anodized finish. The design features precise drainage holes that remove water from the system in marine environments. For optimal performance, the included A5 style buffer body and quick detach receiver end plate are made from 6061 aluminum, the spring is made from high-tensile steel, and the castle nut is made from high-carbon steel. Features8 Position Buffer Tube (A5 Length)Mil-SpecA5 Style Buffer, 3.8ozHigh-Quality Recoil SpringCastle Nut & QD Receiver End Plate