A few inches off the actual heater in the power cable is a special plug that replaced an old style tamiya plug on the first generation units. This plug allows you to disconnect the unit from the power source easily. on the other end is a Deans plug that you can use to hook to your battery, power supply, etc.

You do not want to leave the heater unit hooked to power when it is not on a engine head. It will get very hot and shorten the life span.