Sunleaves Hygro-Thermometer 

With the Sunleaves Hygro-Thermometer, keeping tabs on your indoor garden has never been easier. 

The Hygro-Thermometer displays current temperature and humidity levels and includes a remote probe for a second zone temperature - ideal for domed growing trays!

The Hygro-Thermometer records the high and low points for both the temperature and humidity to help fine-tune your grow room accuracy.

Offers a Centigrade / Fahrenheit exchange to meet your preferences and has a built-in foldaway stand, or mount using the keyhole or Velcro tape.

Humidity measuring range is 20 - 99%. Temperature measuring range from -58 to 158 degree F. Display reading updates every 10 seconds. This Hygro-Thermometer does have an on / off switch.

More info from the Manufacturer (PDF format - Lots of detail.)