Get precise control of your aquarium temperature with Marineland Precision Submersible Heater. With an adjustable temperature dial, high-visibility temperature display and an advanced heating element, this heater makes it easy to keep your freshwater or saltwater aquarium water at the optimal temperature. A flattened mesh heating element surrounds a mica core for superior heat transfer. Features a thermal safety switch that prevents heater failure during use – the heater automatically turns off if the temperature rises above an internal pre-set and turns back on once it cools down. A mounting bracket is included to securely attach to glass. Lifetime warranty – see product packaging for details.Available in eight sizes: 50 watts (for aquariums up to 12 gallons); 75 watts (for aquariums up to 20 gallons); 100 watts (for aquariums up to 29 gallons); 150 watts (for aquariums up to 40 gallons); 200 watts (for aquariums up to 55 gallons); 250 watts (for aquariums up to 70 gallons); 300 watts (for aquariums up to 80 gallons); 400 watts (for aquariums up to 125 gallons).Marineland Precision Submersible Heater is precision-designed for a safer option for both freshwater and marine aquariums. A better, safer heater? Precisely.