JBL ProTemp S aquarium heaters incorporate the latest technology and are suitable for use in both freshwater and marine water aquariums. A protective plastic grid around the quartz glass prevents fish accidentally touching the hot surface and suffering burns. This also protects the very tough safety quartz glass from damage when handled carelessly. A safety protection device in the JBL ProTemp S heater interrupts the electric current in the event of overheating e.g. if the owner forgets to unplug the heater when changing the water and when the heater is left in the dry. Due to the short, compact form the heater can be positioned vertically in almost any household available aquarium. JBL ProTemp S heaters are completely watertight and can be operated fully immersed. A large control dial with clear markings enables the temperature to be easily set in the range of 20 - 34C. A control light shows the operation of the heater. However, an aquarium thermometer should also be used as an addi