Features:Professional Oxygen Detector -- Portable Oxygen (O2) Gas Detector that measures oxygen content in the range 0-25%. The electrochemical gas sensor is used for measurement, and the oxygen detection sensor has stable performance and high precision.Adjustable alarm - when the oxygen concentration reaches the alarm level, the sound and light double alarm. The alarm value can be customized according to user needs.Backlit LCD Display -- The gas meter is small and light, with a large LCD display with backlight, you can see from the screen at a glance even in the dark, easy to carry and easy to read.USB Rechargeable -- Equipped with a 3.7V rechargeable lithium battery, which can be charged through the micro USB interface, and can be powered by a power adapter, power bank, etc.Widely Applicable -- The oxygen detector can be used in metallurgy, power plants, chemical industry, mines, tunnels, underground pipelines and other places to effectively prevent hypoxia and oxygen poisoning.