When plugged into the USB port of a PC installed with the purpose designed software under Windows 2000, XP & Vista (32 bit only), the Lascar EL-USB-RT measures temperature and relative humidity from -20 to +70°C (-4 to +158°F) and 0 to 100%RH. The PC displays the temperature, humidity and dew point (the temperature at which water vapor present in the air begins to condense) in real-time and saves it to a file which can store up to 7 day’s worth of data. This data file is overwritten at the beginning of each new logging session. The software provides the option for the user to save the data file permanently to the hard-drive. Temperature, relative humidity and dew point can be graphed, printed and exported to other applications.