Solid State Relay SSR-25DA And Temperature Controller TD4-SNR, Can Also Worked As Simple Digital Adjustor (Dual Line Display, PID control) Display: Dual display for Fahrenheit(F) and Celsius(C) Range: -1999 to 9999 (depends on the input signal) Main output: SSR, open circuit: 4V, Closed Circuit: 24V 40mA DC Auto-tuning / Manual PID control ( can choose normal alarm output by software) Alarm Output: RELAY: capacity 250V/3A AC, 30V/3A DC