Operation stepsFirst press the PWR button on the aquarium thermometer; then put the sensor probe into the water; the suction cup attached can stick the LCD screen to the side of the aquarium. Easy to readYou can easily read the water temperature through the LCD screen of the aquarium thermometer . The temperature unit can be switched between C and F with the button. Measurement rangeThe measurement range of the aquarium thermometer is -50C ~ +70C / -58F ~ 158F, accuracy is +/- 1 degree Celsius. Dimensions: 583815mm. Power supply: LR44 battery (included). Wide ApplicationThe aquarium thermometer is suitable for fish tanks, aquariums, reptile boxes, incubators, refrigerators, cigar houses, etc. It can protect reptiles, fish and small animals from dangerous temperatures. Package includesYou get 2 aquarium thermometers, each with 1 LR44, 1.5V button battery and 2 suction cups. Probe cable length: 1 meter. NOTE: Do not put the thermometer in water, only the probe sensor is waterproof.