Pet Worx Aquarium Heater 300w  is fully submersible and is suitable for Freshwater and Saltwater Aquariums.  The heater is thermostatically controlled with a temperature range of 16 degrees to 32 degrees C  Its external adjusting know makes it easy to read and adjust the temprature.  It is made of high quality flame retardant plastic, durable heating elements and has a heat resistant quartz tube.  The heater can be placed vertically, horizontally or at any angle and is easy to insall with a strong suction cap.