We all know that air is an indispensable part of our lives. The quality of air is affecting our body and mind, but the air is colorless and tasteless, we can't measure it with the eyes. At this time, we need an air tester to help to monitor the air quality. Features: 2.8" color liquid crystal display (LCD), 320 * 240 pixels. User adjustable alarm threshold for O3 to alert user of elevated levels. It can be used in office, indoor outdoor and detection of ozone residue after disinfection. Large 2000mAh capacity lithium battery. Micro USB charge Low battery warning. Electrochemistry sensor for O3. Temperature and Humidity sensor. AQI for ozone concentration index. Support time and date, self-calibration function. LCD screen, display various parameters. USB charge port for convenient using. With a storage box for easy carrying. Specifications: Material: ABS Color: black+orange Screen size: 2.8in O3 concentration AQI: 0~0.100: Fine 0.100~0.300: Slight 0.300~1.000: Moderate 1.000~4.999: Serious Battery: 1 * lithium battery, 2000mAh (included) Item size: 164 * 74 * 26mm / 6.5 * 2.9 * 1.0in Package size: 280 * 225 * 70mm / 11.0 * 8.9 * 2.8in Package weight: 501g / 1.1lb Packing List: 1 * Air Quality Detector 1 * USB Cable 1 * User Manual 1 * Box