Fortis Manufacturing, Inc., Billet M4 Upper, Stripped, Fits AR15, 223 Remington, 556NATO, Black Color, Anodized Finish WARNING: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov One Piece Billet Design Aircraft Grade 7075 T6 aluminum Military Specification Type III Hard Coat Anodized M4 feed ramp Engraved logos on both sides as well as the top 1913 picatinny rail flat top Light weight at 6.7oz Made in the USA. The Fortis Billet Upper is a precision piece, machined from Billet 7075 T6 aluminum. Like Fortis' other products, they designed this upper with function as well as form in mind. Fortis shaved off the ounces where they could without sacrificing rigidity or strength. The end result is increased function and performance with the design aesthetics that Fortis is known for.