Perfect-Prime CO2000 Indoor Quality Meter/Thermometer/Hygrometer USB CO2 Carbon Dioxide Air Temperature Humidity Datalogger, 5.51" x 4.0" x 1.54", Black/White Monitor carbon dioxide (Co2) level indoors to ensure high air quality is maintained for health and safety Track three readings at the same time: temperature, range: - 10 ~ 70c (14 ~ 158f), humidity, range: 0.1 ~ 99.9Percent, carbon dioxide (Co2), range: 09999 ppm (typical 400 ~ 2000 ppm) Alarm function to notify operators in the area when carbon dioxide (Co2) reaches or surpasses a set limit Meet regulations and pass spot inspections Usb power supply: usb charger or usb power bank compatible with mobile phone power bank and charger