The pro sensors are battery powered but alternatively they except the pro 55int can be powered via an external power supply thejunction box is available as a seperate kit and contains jumper cable junction box 5 volt power adapterthe box should be connected to the pro sensor via a jumper cable and the 5volt adaptor as you can see in above drawing junction box connections the sensor can directly be connected to the junction box instead of the pro sensor only pt 100 sensor