The AR-10/AR-308 upper receiver vise block is precisely machined from high-density polyethylene (HDPE) to securely hold the upper receiver in a bench vise, preventing any risk of crushing, marking or scratching the finish. To use, secure the assembly in the vise, slide the upper receiver onto the block and insert the provided locking pins. Compatible with all standard AR-10/AR-308 upper receivers High-density polyethylene (HDPE), a thermoplastic polymer known for its high strength-to-density ratio, is extensively utilized in applications requiring robust, lightweight and chemically resistant materials Incorporates integrated locking pins for enhanced security and stability Manufactured in the United States