Sensor Type:Electrochemical, Catalytic, IR sensor (Oxygen, Carbon monoxide, Hydrogen Sulfide, Hydrogen, Ammonia, Sulfur Dioxide, Nitrogen Dioxide, Nitric Oxide, Combustible (CH4) ) Dimensions: Main board : 67 mm x 27 mm x 36 mm Small sensor board : 21 mm x 27 mm Input Voltage:Analog 10-30 V DC or Digital 5 V DC Analog Signal Outputs: 4-20mA Digital Signal Outputs: TTL ( 3V Level ) TTL Parameter Baud rate : 9600 bps, Parity : none, Stop bit : 1, Data bit : 8 Calibration Switch: O2 : ZERO Calibration 10 sec, SPAN Calibration 3-8 sec More Type : ZERO Calibration 3-8 sec, SPAN Calibration 10 sec