This heavy-duty block securely clamps into the magwell of the lower receiver of AR-10/.308cal AR-type rifles to prevent damage or movement during repair, assembly and cleaning. The double sided design fits Armalite, DPMS, Remington, SR-25, and many other variants. It is constructed of impact resistant, glass-filled nylon.A heavy-duty block securely clamps into the magwell of the lower receiver of AR-10/308 Cal AR-type rifles to prevent damage or movement during repair, assembly and cleaning. Double sided design fits ArmaLite, DPMS, Remington, SR-25, and many other variants. Constructed of injection molded black polymer. Features: AR-10/308 cal AR type rifles lower receiver magazine well vise block Heavy-duty block clamps into the magazine well of the lower receiver Helps to prevent damage or movement during repair, assembly and cleaning Double sided design fits Armalite, DPMS, Remington, SR-25, and many other AR type rifles Made of injection molded black polymer Made in USA