Features: Professional for testing the oxygen content of the air, with 0-25 percent oxygen content detection range. Adopts with good quality electrochemical sensor, the O2 meter respond quickly yet has high precision. 3.7V 1000mAh large capacity rechargeable lithium battery has long stby time low power consumption. 2.7-inch large LCD display screen, the green backlight for clearly reading the measured data. Compact portable size with ergonomic design is easy to use, high quality rubber buttons has comfortable h feel during operation. Sound light dual-alarm when the measured result exceed the preset alarm value. The O2 tester has stable performance high accuracy that suitable for home use, agriculture, chemical industry, etc. Specifications: Material: ABS Voltage: AC100-240V, 50 or 60Hz Output: DC5Vu00B15 percent , 1000u00B150mA Measuring Range: 0-25 percent Resolution: 0.1 percent Temperature: -10-50 Resolution: 0.1 Working Humidity: 0-95 percent RH Power Supply: 1 3.7V, 1000mAh rechargeable li-ion battery Screen Size: 4.4 5.3cm or 1.73 2.08in Storage Box Size: 23 20.5 5cm or 9.06 8.07 1.97in Item Size: 18.3 6.5 3cm or 7.20 2.56 1.18in Item Weight: 245g or 8.64oz Package Weight: 743g or 26.21oz Package Size: 25.5 21 5.7cm or 10.04 8.27 2.24in Package List: 1 Detector 1 USB Cable 1 Storage Box 1 Manual (English)