Dymax Vortex Cooling Fan W-5 is a hang on type cooling system which uses vortex technology with conceal type design for safety purposes. Reducing water temperature in the aquarium is one of the problems that needs solving, especially in reef and aquatic plant tanks. The DYMAX Cooling fan is made to keep the aquarium temperature as low as possible. Besides being a compact design with powerful performance, the fan is also equipped with a clip-on feature that can be secured on most edges of your aquarium. It also has a flexible arm feature that enable the fan to blow at any desired angle. Capable of reducing water temperature between 2-4 degree celsius from room temperature on DC voltage.