This vise block allows the user a "third-hand" to work on and install parts to AR-15 / M-16 lower receivers. The vise block is clamped into the users vise, and the block is then inserted into the lower receivers magazine well, and is held in place by the magazine catch. Constructed of a black injection molded polymer. Features: Vise block allows the user a "third hand" to work on and install parts to AR-15/ M16 lower receivers Vise block clamps into the users vise, then inserted into the lower receivers magazine well, and is held in place by the magazine catch Made of injection molded black polymer Made in USA