The TacFire AR-10 Lower Vise Block features a solvent-resistant, precision-molded polymer construction, providing a secure and non-marring mounting surface for your lower receiver during maintenance, assembly, and disassembly. It locks firmly into your magazine well and clamps securely in a bench vise, giving you a stable platform to work on your rifle without risking scratches, dents, or structural damage. Compatible with AR-10 lower receivers only.