Spikes Tactical SFT50M4: The Spike\'s Tactical M4 flat top upper receiver is machined from a Mil-Spec 7075 T6 Aluminum forging with a durable Type III Hardcoat Anodized finish that also features laser engraved T-Markings, M4 feed ramps cut into the receiver before Anodizing to avoid future reliability issues, and finished with the Spike\'s Tactical spider logo. A forward assist and ejection port door cover are also already installed in the upper.