With a simple device you can now detect both the heat and humidity levels in your terrarium, incubator or other pet enclosures through the Zoo Med Digital Combo Thermometer Humidity Gauge. This unit features a quick-reading digital display with your choice of Fahrenheit or Celsius by a simple switch for your convenience, which should be placed in a dry location outside of the enclosure. To turn it on, press the power button once, and to turn it off press the power button for 5 seconds. The hygrometer and thermometer have independent remote sensors that can pick up data from different locations. Submerge your sensor underwater, or test out specific spots in the enclosures air by mounting with suction cups. The LR44, 1.5 v battery is included so you can begin use right away!