The Onset HOBO MX1102A Bluetooth Low Energy (BLE), Smart-Enabled CO2, Temperature and Relative Humidity (RH) Data Logger makes it more convenient than ever to measure and record CO2 in buildings and other non-condensing environments. It measures CO2 from 0 to 5,000 parts per million (ppm), and the free HOBOmobile app allows you to access data right from your mobile phone or tablet within a 100-foot range. The MX1102 also features a USB port so it can be used with a computer running HOBOware Pro graphing and analysis software.