Heavy-duty blocks enable secure clamping of AR-15/M16 receiver halves in a vise, eliminating the risk of crushing, twisting or distorting them during vise pressure application or barrel nut torqueing. These blocks ensure the rifle remains stable for safe and efficient cleaning, assembly and repair. Constructed from unbreakable urethane, the vise block absorbs all clamping force, thereby preventing damage or distortion to the expensive lower receiver. To use, insert the block into the magazine housing from either the top or bottom, then secure the opposite end in your bench vise. The magazine catch locks onto the block, providing a safe and secure hold for assembly, disassembly, cleaning or repair. The block will not mar or scratch the finish. It fits snugly in most receivers and may require filing for compatibility with others.

• High-density urethane polymer material