Guntec USA AR-15 5.56mm Complete Upper Kit Black. The goal is to distribute excellent quality at an economical value. Specifications for Guntec USA AR-15 5.56mm Complete Upper Kit: Manufacturer: Guntec USA Caliber: 5.56mm Threads per Inch: 1/2x28 Finish: Anodized Color: Black Fabric/Material: 4150 Steel Magazine Included: No Features of Guntec USA AR-15 5.56mm Complete Upper Kit 5.56 Upper Receiver. 5.56 Charging Handle. Custom Short Gas Tube. Crush Washer. Kit does not come assembled. 5.56 Complete BCG. Forward assist asssembly. Steel Low Pro .750 Gas Block. Mini muzzle brake. 5.56 Ejection door assembly. 4in M-LOK compression handguard with barrel nut & hardware. Package Contents: Guntec USA AR-15 5.56mm Complete Upper Kit Guntec USA GT-C-UPPER-5.5-MLK-MINI: AR-15 5.56mm Complete Upper Kit Black