The Fusion Air Pump has a patented Baffle system, which is a series of chambers that are interlinked by small openings. These chambers not only absorb the sound, making the Fusion Air Pumps amazingly quiet, they also create pressure as the air is pushed through each small opening, producing a powerful air flow! Also features an air control knob, which gives the user optimal and precise air flow control! Models 400 and up feature adjustable rheostat to control the amount of air output. Rated for up to 30 gallons with single outlet.