The Cobalt Aquatics 20 watt Mini-Therm is a compact, fully submersible heater designed for use in small aquariums up to 4.8 gallons. Equally capable in both freshwater and saltwater environments, this high quality heater will raise the temperature in your aquarium up to 10 degrees Fahrenheit above the ambient temperature. The plug & play Mini-Therm is designed for constant operation, eliminating the need for adjustments. It features an ceramic radiator that delivers even heat distribution from the heating elements, and a shatterproof thermal-plastic polymer casing to ensure protection of your aquarium and the heater's internal components. The included suction cup mount allows effortless positioning anywhere in your aquarium. Ideal for freshwater and saltwater aquariums, and semi-aquatic terrariums. For quality assurance and peace of mind, the Cobalt Aquatic 20 watt Mini-Therm Heater is backed by a 3 year limited manufacturer's warranty.