To ensure unit performance, the UV LED bar has a single input and output socket for the Power Cable or Daisy Chain Cable depending on the setup. For this reason, thePower cables and Daisy Chain cables are sold separately. You will need one power cable for each setup, plus a daisy chain cable for each extra UV Bar that is added to the setup. eg. If you are adding two UV bars to a Zeus unit, you will need one power cable and one daisy chain cable. If you want to run a single UV bar by itself, you will need one power cable. If you are adding a UV bar to an existing UV Bar setup, you will need one daisy chain cable.