Tiny titan aquarium heater by Hygger Aquatics
Easy To Hide Compact Design -- Slim flat profile mini aquarium heater measures 4.3''x 1.8''x 0.9'', which is quiet & space saving.  25W aquarium heater is suitable for 2-5 gallons.
Convenient Digital Display -- LED digital readout is convenient and accurate, displaying real time water temperature and indicator light. It will be red when heating, green light when the proper temperature has been reached. Allows you monitor aquarium water temperature at any time.