Features: Professional for testing the oxygen content of the air, with 0-25% 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 standby time and low power consumption. 2.7-inch large LCD display screen, and 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 hand feel during operation. Sound and light dual-alarm when the measured result exceed the preset alarm value. The O2 tester has stable performance and high accuracy that suitable for home use, agriculture, chemical industry, etc. Specifications: Material: ABS Voltage: AC100-240V, 50/60Hz Output: DC5V+/-5%, 1000+/-50mA Measuring Range: 0~25% Resolution: 0.1% Temperature: -10~50 celsius Resolution: 0.1 celsius Working Humidity: 0~95%RH Power Supply: 1 * 3.7V, 1000mAh rechargeable li-ion battery Screen Size: 4.4 * 5.3cm / 1.73 * 2.08in Storage Box Size: 23 * 20.5 * 5cm / 9.06 * 8.07 * 1.97in Item Size: 18.3 * 6.5 * 3cm / 7.20 * 2.56 * 1.18in Item Weight: 245g / 8.64oz Package Weight: 743g / 26.21oz Package Size: 25.5 * 21 * 5.7cm / 10.04 * 8.27 * 2.24in Package List: 1 * Detector 1 * USB Cable 1 * Storage Box 1 * Manual (English)