Guntec USA AR-15 Upper Receiver Assembly Kit. 56 Charging Handle 5.56 Trap Door Assembly Specifications for Guntec USA AR-15 Upper Receiver Assembly Kit: Manufacturer: Guntec USA Fabric/Material: T6 Aluminum Gun Make: AR Platform Gun Model: AR-15 Weight: 10 oz Features of Guntec USA AR-15 Upper Receiver Assembly Kit 5.56 Trap Door Assembly Forward Assist Assembly 5.56 Charging Handle Package Contents: Guntec USA AR-15 Upper Receiver Assembly Kit What firearm models does the manufacturer say Guntec USA AR-15 Upper Receiver Assembly Kit is compatible with? The manufacturer says that Guntec USA AR-15 Upper Receiver Assembly Kit is compatible with AR-15GUNTEC USA GT-URK: AR15 Upper Receiver Assembly Kit