DPMS .223 Remington/5.56x45mm NATO Upper Receiver Claw Block One Size. Made of a solid one piece high strength polymer the Claw is extremely durable. Simply clamp the Claw into a bench vise slide the upper onto the Claw secure with the two holding pins and begin installing your barrel and components. Specifications for DPMS .223 Remington/5.56x45mm NATO Upper Receiver Claw Block: Manufacturer: DPMS Caliber: .223 Remington 5.56x45mm NATO Fabric/Material: Polymer Package Contents: DPMS .223 Remington/5.56x45mm NATO Upper Receiver Claw Block DPMS DP51655131035: .223 Remington/5.56x45mm NATO Upper Receiver Claw Block One Size