Easy-to-use digital aquarium thermometer includes a large easy-to-read LCD display. Provides up-to-the-minute accurate temperature readings within 0.1 degree in both Fahrenheit and Celsius. Suction cups affix the screen to the outside of your tank and the temperature gauge to the inside of your tank submerged in water. LR44 batteries are included so you can start measuring temperature as soon as you open the package. To turn the thermometer on simply press the “On” button and you’re ready to measure your aquarium’s temperature and ensure your fish’s health.