Quiet; economical filtration performance of the classic Whisper20 Power Filter is great for freshwater or saltwater aquariums. Energy-efficient designs feature low-wattage motors and adjustable flow control. Bio-Foam cultivates and maintains a bacterial bed for biological filtration; while easy to replace Bio-bag cartridges take care of chemical and mechanical filtration. Bio-Bags included. Measures: 7 in. x 3.5 in. x 7 in. The Whisper 20 is rated for aquariums up to 20 gallons; and has a maximum flow rate of 105 gph. For more information about the Tetra Whisper 20 Power Filter; see the Manufacturer's Instruction manual. For more info on Hang-on Power Filters; please see Power Aquarium Filter Basics.