The M4E1 Threaded Upper Receiver features an angular machined design that helps it stand apart from standard mil-spec upper receivers. It is threaded to accept a standard AR15 barrel nut and forged from 7075-T6 aluminum and precision machined to work with all mil-spec AR15 parts. The M4E1 features a picatinny profile, M4 feedramps, and .250 takedown pin holes. This model has a black hardcoat anodized finish. NOTE: This model does not include port door or forward assist.