Tropical-Reef Hydro-Ripple Hang on Filters are designed to be hung onto the back of the aquarium. 
Three Sizes Available:
HR-250 - 250L/H Flow Rate, Power 3.5W.
HR-320 - 320L/H Flow Rate, Power 5W.
HR-450 - 450L/H Flow Rate, Power 7W.
They provide very high levels of aerobic filtration.
They are ideal for aquariums where a submersible filter would take up too much space.
Hydro-Ripple Hang on filters are also ideal as an additional filtration system to supplement other filters.
- They provide Excellent oxygen levels achieved due to the design with the returning water cascade, which also adds a nice additional feature to your tank! 
Built in power heads offer high water turn over rates - High quality media content. 
Features: 
Quiet Operation Highly Efficient Filtration. 
Compact Design Easy Restart Without Adding Water.
Effectively skim away surface oil film caused by bio waste.
Special Cascade flow design improves dissolved oxygen levels.
Adjustable flow regulating valve to achieve optimal flow rate.