The all new Cobalt Aquatics MINI-Therm compact and fully submersible heaters feature a constant ON design, specifically for small aquariums up to 5 gals. The heater casing is made from a thermal-plastic polymer that is shatterproof. An internal ceramic heat radiator that provides even and the best heat distribution from the heating elements. Perfect for freshwater and saltwater aquariums and terrariums. 3 year warranty.