The 1820-28-A3 is a Signal and Dataline Protector, designed to protect sensitive electronic circuits and components from damaging surge voltages and currents. Their extremely fast response and low clamping voltages make them particularly suitable for the protection of signal and data lines associated with computer, data communication, instrumentation, broadcasting and industrial controls. They may be used directly with EIA standard interfaces RS-232, RS-422, RS-423, RS-485 and with 20 and 50mA instrumentation loops. Flame-resistant epoxy-filled housing. Operating temperature ranges from -40°C to 60°C.