Take this handy humidity and temperature gauge with you wherever you go, and it will run on a long-lasting 3V lithium battery for extended use. The small Extech 445580 humidity/temperature pen measures humidity from 10 to 90% RH and temperatures from -10°C to 50°C (14°F to 122°F). This utility tool is suitable for field work since it saves maximum and minimum readings until the memory is cleared and has a data-hold button for quickly fluctuating measurements. The meter comes with a pocket clip and a 3 volt lithium battery.