Fluval Pro Adjustable Air Diffuser, 2-PackCompatible with all aquarium air pumps, the Fluval Air Diffuser is easy to install, quiet to operate and offers adjustable flow for customized bubble control, making it an ideal alternative to traditional air stones.Easy to install, quickly connects to airline tubingSecure suction cup mount for versatile positioningLarge easy-grip dial for simplified adjustmentTurn dial clockwise to increase pressure and counter-clockwise to reduce pressureProvides effective water surface agitation for better oxygenation