... GasDetected Gas: O2, CO, H2S, SO2, CL2, HCN, NO2, NH3, H2 Calibration: self-calibration, with automatic attenuation compensation functionSensor type: electric-chemical sensor (changeable ... )Cell: 3.0V Li Cell (changeable)Explosive-proof Level: European Standard ExiallBT4Dimension: 93mm*50mm*27mm CO Portable Gas Detector