Heavy-duty blocks are designed to securely clamp AR-15/M16 receiver halves in a vise, effectively eliminating the risk of crushing, twisting or distorting them during the application of vise pressure or barrel nut torqueing. These blocks provide stability to the rifle, ensuring safe and efficient cleaning, assembly and repair. Made from unbreakable urethane, the vise block absorbs all clamping force, thus preventing any damage or distortion to the costly lower receiver. To use, simply insert the block into the magazine housing from either the top or bottom and then secure the opposite end in your bench vise. The magazine catch locks onto the block, offering a safe and secure hold for assembly, disassembly, cleaning or repair. The block is designed not to mar or scratch the finish and fits snugly in most receivers, although some may require filing for compatibility.

• High-density urethane polymer material