Marineland Precision Submersible Aquarium Heater

100 Watt – 10.25" Long – (Aquariums up to 29 Gallons), 150 Watt – 12" Long – (Aquariums up to 40 Gallons), 200 Watt – 13.5" Long – (Aqauriums up to 55 Gallons), 250 Watt – 14.5" Long – (Aquariums up to 70 Gallons), 300 Watt – 15" Long – (Aquariums up to 80 Gallons), 400 Watt – 18" Long – (Aquariums up to 125 Gallons)