This is a solid-state relay option for NCD solid-state relay controllers. Though we allow you to select a solid-state relay option at the time of purchase, you can always order our controllers unpopulated and customize the controller to your exact needs by adding relays to your cart. We will work with you to determine which location you would like each relay installed. Simply add the relays you need and we will get them installed and ship you a fully functional solid state relay controller with the any combination of solid state relays you may need.