Designed for use with the Best Gun Vise, this attachment is the handiest tool an AR-15 owner could ask for. This ingenious center support provides a premium base for cleaning or light gunsmithing on your AR-15, in breech or closed position. A bolt-service station locks bolt in for servicing extractor pin. Built-in hammer stop prevents damage to lower receiver. Center section rotates 180° in 7° increments and locks securely in place at desired location. Mag well arm is removable. Constructed of durable, solvent-resistant polymer that will not mar gun surfaces. Includes fasteners for attaching to vise or securing to bench top. Not to be used as a shooting rest.