As an electrical control device, the relay is in fact an "automatic switch" that controls the operation of a large current through a small current, so that it has functions of automatic regulation, safety protection as well as circuit conversion. Many automobile and motor devices need a relay to control the circuit, such as led work light, fog lamps, starter, wiper, fans, speakers, central locking, alarm, electric windows, etc. <br><br> MICTUNING 12V 40A relay is a great replacement for light bar and suitable for most LED light bar wiring harness kit.<br><br></b> Package included:</b> 1x relay.