Outerwild AR9 9mm Billet PCC Upper Receiver Black Anodize. Machined from a solid billet of 7075-T6 aluminum hand deburred tumbled and hard coat anodized.Ensure that every upper is well within spec and will function perfectly for your build. Specifications for Outerwild AR9 9mm Billet PCC Upper Receiver: Manufacturer: Outerwild Color: Black Finish: Anodize Fabric/Material: 7075-T6 Aluminum Caliber: 9mm Luger Gun Make: AR Platform Gun Model: AR-9 Package Contents: Outerwild AR9 9mm Billet PCC Upper Receiver What firearm models does the manufacturer say Outerwild AR9 9mm Billet PCC Upper Receiver is compatible with? The manufacturer says that Outerwild AR9 9mm Billet PCC Upper Receiver is compatible with AR-9Outerwild 4022-0909-024-O: AR9 9mm Billet PCC Upper Receiver Black Anodize