A contactor is an electrically controlled switch used for switching an electrical power circuit, similar to a relay except with higher current ratings and a few other differences.Relays are used where it is necessary to control a circuit by a separate low-power signal, or where several circuits must be controlled by one signal. A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor. SKU: 3RH19211CA10 Product Features: 1NO FRONT MOUNTED AUX. CONT. BLOCK FOR SIZE – S2-S12