Handheld/Portable hazardous gas transmitters are designed to protect personnel safety by detecting the concentration of dangerous gases H2S or CO in extreme environments. The instrument can be used in variable and abnormal climatic environments such as deserts or the Arctic Circle. The handheld/Portable gas detector is compact and lightweight, and can be easily clipped onto a belt, shirt pocket, or safety helmet. The extra-large LCD screen clearly displays gas concentration, type, peak value, and high and low concentration alarm levels. If the current high or low gas concentration exceeds the preset limit, the instrument alerts the user via audible, visual, and vibration alarms. Features: Continuous display of CO or H2S concentration; High and low concentration audible, visual, and vibration alarms; One AA/size 5 alkaline battery allows continuous operation for 500 hours; Extra-large LCD display: PPM readings and battery life; Peak hold; U.S. Patent: Integrated calibration cap and one-key automatic calibration. Specifications: Housing: Impact-resistant composite material, RFI (Radio Frequency Interference) resistant; Dimensions: 86 mm x 58 mm x 19 mm; Weight: 98 g; Sensor: Electrochemical principle; Range: CO: 0~999 ppm, resolution 1 ppm; H2S: 0~500 ppm, resolution 1 ppm; Power: 1 AA/size 5 alkaline battery (approx. 500 hours); Temperature Range: -20~50℃; Humidity Range: 15~95% RH; International Certifications: USA and Canada UL and cUL - Class I, Groups A,B,C,D; European CENELEC (ATEX) and Australia: - Eex ia Iic T4; China Coal Mine Safety Certification (MA)