The DC Latching Solenoid is used to convert automatic sprinkler valves so they can be operated with the HRC 990 Battery Operated Sprinkler Controller. The DC Latching Solenoid is designed to operate on Rain bird, Hunter, or Hydro-Rain valves. The HRC 900 battery-operated controller sends a quick DC pulse to operate the solenoid, so you need a DC latching solenoid to operate correctly. When using the HRC 990 the keyed plug can only be installed one way, simplifying the installation process. The DC latching solenoid has one black wire for the common wire and one red wire for the station wire. It is important that the wires are connected correctly for proper operation. Black connected to the C or COM (common) terminal inside the controller, and the red wire connected to the appropriate station terminal.