The Juwel Digital Thermometer measures the water temperature in your aquarium with a large, easy-to-read digital display. It accurately monitors water temperature in a range from 16 to 42°C with an accuracy of +/-1°C and has a battery life of up to a year. This thermometer is suitable for use in both freshwater and saltwater aquariums and features an external sensor with an extra-long cable. It is designed for universal use with any aquarium, including Juwel aquarium covers.