The XAR-O O2 gas detector continuously display the ambient concentration of oxygen and activate its audible alarms whenever the preset setpoints are exceeded. It can be widely used in the car, touring car, garage, food/fruits/goods container, petrochemical, power plant, telecom, medicine, mine, heavy industry, army, food industry, gas industry, and other confined spaces for personal safety. This O2 Gas Detector uses two-electrode electrochemical technology, operating by the diffusion principle, for determining the concentration of oxygen in air samples. XAR-O can implement ambient air calibration (20.9%) when needed (such as annually). It has two alarm setpoints: Warning (O2: 23.5%, high alarm) and Danger (O2: 19.5%, low alarm). Oxygen Sensor Specification : Measurement Range : 0 ~ 30.0% vol. O2; Resolution : 0.1% vol.; Sample Method : Diffusion; Baseline Drift (-10-50°C) : <1% change in output @ 3 months; Response time : <15 seconds from 20.9% to 0% O2; Operating : -10°C to 50°C (14°F to 122°F), 5~95% RH non-condensing; Power Supply : Four AA Alkaline Batteries; Dimensions : 75x165x25 mm (2.95x6.49x0.98"); Weight : 136 grams (4.8 oz.) without batteries. MATERIALS SUPPLIED: (1) XAR-O O2 Gas Detector; (2) Plastic Toolbox; (3) Telescopic Wand with Tripod; (4) English User Manual.