Features: Accurate detection of CO2s. Large screen displays HCHO TVOC PM2.5 PM10 PM1.0 CO2s Temperature Humidity and time. Hundreds of ventilation holes in the rear not only accelerate the convections between the air and the machine, thus achieving effective detection, but also provide a good heat dissipation effect. The product enters the standby state after 30 minutes without operation, during which time the battery power and air quality statuses are displayed. Using special quality electrochemical detection module, good accuracy, stable performances, strong anti-interference ability, low consumption, long box life. The product does not need to be calibrated, and can be test on boot to accurately detect carbon dioxide. Large screen displays electricity, CO2s, temperature and humidity. Different font colors show different air quality, 400ppm-1000ppm: Green, normal. 1001-3000ppm: Yellow, concentration is slightly high. Greater than 3000ppm: Redness, concentration is extreme high. Specifications: Material: ABS Voltage: 3.7V Battery: Built-in 2000mAh Battery Size: Approx. 160x90x41mm/6.30x3.54x1.61in Note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1x CO2s Tester 1x Manual 1x USB Cable