Hooker Electric provides the highest quality electric solenoid available for continuous duty. Solenoids are relays which are commonly used to remotely switch a heavier current. By using a solenoid, the amount of heavy wiring needed to power the load is reduced, since the control circuit mounted inside the cab typically utilizes a smaller wire gauge. Solenoids are commonly used to control starter and winch motors, and they have many other uses on vehicles and electronics of all kinds. When the control circuit is energized, the electromagnetic force induced in the coil attracts the plunger, which moves to close the load circuit. When the control circuit is de-energized, the spring-loaded plunger returns to its normal state and the load circuit is broken. In continuous duty applications, energization of the coil causes heating, therefore the solenoid housing will become warm even in normal operation. The 85A SPST Continuous Duty Solenoid for 4500 Bait Pump is a solenoid featuring a PVC-coated plated steel housing and copper contacts and is rated for the Hooker Electric Bait Pump 4500. Note: The bait pump solenoid is not included with the purchase of a Hooker Electric Hi-Flow Bait Pump.