Allows 2 digital I/O lines to each control a relay or other moderate load. The 4-pin design plugs into the standard DIO/DIO/GND/VS screw terminal block found on LabJacks such as the U3, U6, UE9, T7, and T4. Each DIO controls a switch to ground (i.e. open-collector) that can hold off up to 50 volts and can sink up to 200 mA.