Aqueon Submersible Aquarium Heater, 300 Watts, Up to 100 Gallons

Fully submersible, auto shut-off when overheats, resets when cools down
Electronic thermostat stops heating once set temperature is reached
Precise temperature setting adjustable to 1° F (68-88° F)
Shatter-resistant
LED light turns on when aquarium water is being heated, automatic safety shut off and overheat protection
For fresh or saltwater aquariums up to 100 gallons