Usage Tips:Features: 2.8 inch LCD HD color display. Display the oxygen concentration and temperature and humidity values, the curve interface. Oxygen excessive alarm buzzer sound (excessive alarm sound can be eliminated by pressing any key) + digital color change (alarm value default standard value), you can set 1%-30% alarm value. Data saving function (can store 100000 data), set timing storage, delete data, view historical data. Please note: the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! The display brightness adjustment 5%-100%, the default brightness of 60%, 10 seconds after the screen saver minimum brightness, any key can be restored to 60% brightness. Celsius C and Fahrenheit F switch, long the / key to switch. Specifications: Model: A8 Material: ABS Display Method: 2.8 inch TFT full color LED backlight LCD screen Oxygen Measurement Range: 0-30%VOL Oxygen Resolution: 0.1% Temperature Measurement Range: -9~55 Humidity Measurement Range: 0%RH~100%RH Lithium Battery Capacity: 2500mAh Standard Charging Voltage: 5.00.5V Color: As shown Package Contents: 1 x Handheld Oxygen Concentration Detector Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.