HDE Digital Aquarium Thermometer Fish Tank Thermostat Water Temperature Control Large easy to read display with easy to apply suction cup for secure convenient placement Submerge probe in to water to measure the aquariums temperature (Do not submerge the display) Accurate temperature readings to within 0.1 degree | Temperature range -50c~ + 70c. Operating temperature -10c~ +50c Includes LR44 Batteries | Size of unit: 2" x 1.25" Package Contents: 1 x Battery; 1 x Digital Thermometer; 1 x Probe