Betta Thermal Compact Submersible Aquarium heater reliable circuit and high quality materials ensure output of heat and keeps the water temperature steady inside the aquarium. Temperature can be adjusted between 20 – 34 deg C. Advanced design. Totally submersible. Manual temperature controller. Mains power indicator. Waterproof double seal material for safety. Aquarium heater/thermostat – for aquariums from 5-20litres.