The 849PC03A is an Eaton Mechanical Interlock, designed for a two-pole, two-lock design that maintains continuity within two control circuits. This device is used with a variety of starters, contactors, and switches, preventing undesired operation when used with enclosed wiring devices. It consists of four distinct parts: a body, actuator, auxiliary contacts, and a base. The body is constructed from thermoplastic, and it serves as the mechanical interface between the actuator and the auxiliary contacts. The actuator is made of steel and has a spring-loaded retaining clip, which locks the operating elements in the closed position. The auxiliary contacts are single-pole, double-throw type switch contacts. They are normally open until actuated by the actuator, which causes them to close and make a circuit. The base is made of zinc, and is used for mounting the device to the enclosure.