Dimensions: 1 1/2"diameter 4"long. Inlet: 1/4"- 3/8"barb. Recommended Air Flow: CFM.2. Maximum Air Flow: CFM 1.1. These EPDM rubber air diffusers are incredibly strong and are ideal for pond aeration and circulation. An excellent choice for pond and water garden aeration Barbed inlets have multiple size barbs, simply cut to fit the size tubing you are using.