The Extech 445580 humidity and temperature measuring device is also suitable for use on the move with its long-life 3V lithium battery with maximum service life. The slim humidity/temperature pen takes humidity measurements between 10 and 90% RH and records temperatures from -10°C to 50°C (14°F to 122°F). This tool is ideal for on-site measurements and stores the measured maximum and minimum values until the memory is cleared. The meter has a button to record rapidly fluctuating readings. It comes complete with pocket clip and 3V lithium battery