The Fluval adjustable Diffuser is compatible with all aquarium air pumps with 4/6 mm hose connector. The 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.Fluval adjustable Diffuser+ easy to install, quickly connects to airline tubing+ secure suction cup mount for versatile positioning+ large easy-grip dial for simplified adjustment+ turn dial clockwise to increase pressure and counter-clockwise to reduce pressure+ provides effective water surface agitation for better oxygenation+ Dimensions: 3 x 3 x 5.5 cm (LxWxH)+ 2 pcs. content