S.T. International Microchip Controlled Digital Aquarium Heater with Thermal Powder Diffusion, 300-watt RealMicro-Chip controlledheater thatkeeps the water temp to within 1Fof your setting Proven energy-saving, up to 50% Auto shut-off few minutes after leaving the water - Heater won't Crack Fully submersible and truly water-proof 2-in-1 LED indicator and thermometer