Continuous detection of toxic gases and oxygen in explosion hazardous area with flameproof structure. Self-diagnosis function with built-in Microprocessor. Easy replacement with a cartridge type sensor. Digital flow sensor to maintain regular flow rate Fast response of gas leakage with a high efficient pump inside. Stable quality and proved detection principle for service life Excellent selectivity by adapting detection principle only for toxic gases & oxygen. Superior performance for detecting gases below TLV. Auto calibration and program setting with a magnet bar. 4-digit digital gas concentration display. 4-20mA (Current source or Sink) output signal. Easy configuration of monitoring system by RS-485 Modbus communication. 3-Wire Type. 2-stage alarm, 1-trouble display, and relay contact output. Calibration and maintenance by one-man.