Marineland Mini Heater 10W Shatterproof A heater that features shatterproof thermal plastic in a single piece injection molded case. It is fully submersible and its small size allows placement in virtually any location. Perfect for those small aquariums of up to 3 gallons. The automatic thermostat is preset at 78 with an accuracy to +/-1. Use of a thermometer is still highly recommend though. It also features a Safety shutoff shuts down heater if left out of the water and will restarts automatically when in put back in the water.