... alarming point can be adjusted Function: Portable Gas Detection for Oxygen and Toxic GasDetected Gas: O2, CO, H2S, SO2, CL2, HCN, NO2 ... , NH3, H2 Calibration: self-calibration, with automatic attenuation compensation functionSensor type: electric ... -proof Level: European Standard ExiallBT4Dimension: 93mm*50mm*27mm SO2 Portable Gas Detector