Fluker's Thermometer - Hygrometer Combo helps you establish an appropriate Environmental Temperature Range ETR within your pet's enclosure. 78-82 degrees F and 60-80% Humidity for most Hermit Crabs Fluker recommends using two thermometers mounted at opposite ends of the enclosure to help you monitor the ETR regularly. Directions: Attach combo dial to the inside of your Hermit Crabs enclosure. br/>Sold in Quantity of: 1