This is a precision oxygen concentration instrument, it use electro-chemical type gas sensor to measure the gas, it can quickly response to oxygen, can be manual setup the alarm level with light and sound. Applicable at home, workshop, petroleum refining, petrochemical plant, oxygen content detection in trains and automobiles and industries and plants using oxygen etc. Features: PROFESSIONAL TOOL: The O meter is a device that detects the presence of oxygen (O) gases in an area, often as part of a safety system. The professional detector adopts the electrochemical principle, which gives a quick and accurate measurement. POWERFUL FUNCTION: Sound and light dual-alarm when O gas concentration reaches the level of the alarm. With a large LCD screen display the measured results, you can get gas concentration and temperature at a glance. RECHARGEABLE BATTERY: 3.7V rechargeable lithium battery, with micro USB interface, can be charged through the USB interface of the phone power adapter, computer, etc. Also you can use while charging. HANDHELD SIZE: The gas meter is compact and lightweight, professional designed to fit comfortable in your palm, easy to carry and operate. WIDELY APPLICABLE: The oxygen detectors can be used in car, metallurgy, power plant, chemical, mine, tunnel, underground pipelines and other places, effective prevention of hypoxia and oxygen poisoning. Specifications: Material: ABS Detecting Gas: Oxygen (O) Measuring Range: 0~100% VOL Resolution: 0.1% Basic Error: ≤±3% F·S Temperature Range: -10~50 Humidity Range: 1%RH~99%RH Response Time: ≤15 seconds Recovery Time: ≤15 seconds He Principle of Sensor: Electrochemical principle Display: Large screen segment type liquid crystal display Alarm Mode: Acoustic and light double alarm, can be set the alarm value and alarm sound separately Battery: 3.7V Rechargeable lithium battery Operation Time: 90 Hours (Continue working) Working Temperature: -10~50 Working Humidity: 0-95%RH (non-condensing) Item Size: 205.2 * 63.8 * 33.3mm / 8.07 * 2.51 * 1.31in Item Weight: 205g / 7.23oz Package Weight: 669g / 23.59oz Package Size: 25.5 * 21 * 6cm / 10.04 * 8.26 * 2.36in Package List: 1 * Oxygen Detector 1 * USB Cable 1 * Hose 1 * Carrying Case 1 * User Manual (English)