Fusion Air Pumps have been designed with this in mind, each featuring a patented baffle system. This series of chambers is interlinked by small openings and not only absorbs sound, making the Fusion Air Pumps amazingly quiet, it also creates pressure as the air is pushed through each small opening. Pump features of 400 and above have an air control knob for precise air flow control. Enjoy quiet operation and the air output strength necessary to run airstones and air-driven ornaments and filters. Flexible, rubber feet absorb vibrations to further reduce noise. Use Fusion air pumps to promote proper gas exchange.