Built to last and machined to perform, the NBS AR-15 Assembled Upper Receiver starts life as a 7075 aluminum forging and is precision machined to military specifications. Featuring an M4 flattop profile with M4 feed ramps, this upper is finished in a durable Type-3 Mil-Spec hard coat anodizing for long-lasting corrosion and wear resistance. Comes fully assembled with forward assist and dust cover assemblies - ready to build on right out of the box. Specifications: Profile: M4 Flattop Material: 7075 Aluminum Forging Finish: Type-3 Mil-Spec Hard Coat Anodizing Feed Ramps: M4 Backed by our 30 Day Satisfaction Guarantee. You can install it, run it, beat it up and if you're not happy for any reason, send it back within 30 days for a full refund.