Steps for UsageFirst press the PWR button of the aquarium thermometer; then put the sensor probe into the water; the attached suction cup can stick the LCD screen to the side of the aquarium.Easy to ReadYou can easily read the temperature in the water through the LCD display of the aquarium thermometer. The temperature unit can be switched between C and F with the button.Measuring RangeThe measuring range of fish tank thermometer is -50C ~ +70C / -58F ~ 158F, the accuracy is +/- 1 degree Celsius. Dimensions: 2.17 x 1.46 in Power supply: LR44 cell battery (included).Wide ApplicationThlevel aquarium thermometer is suitable for aquariums, fish tanks, reptile boxes, incubators, refrigerators, cigar houses, etc. It can protect reptiles, fish and small animals from dangerous temperatures.Package IncludesYou get 2 Thlevel aquarium thermometers, each with 1 LR44, 1.5 V button battery and 2 suction cups. Probe cable length: 24.88 in. NOTE: Do not put thermometer in water, only the probe sensor is waterproof.