Description These EPDM rubber air diffusers are incredibly strong and are ideal for pond aeration, circulation and destratisfying applications Unlike air stones these diffusers are easy to clean In testing they produce a slightly larger air bubble than air stones which translates into less oxygen transfer into the water, so for fish holding tanks, raceways, fish production ponds, etc. we recommend air stones Barbed inlets have multiple size barbs, simply cut to fit the size tubing you are using An excellent choice for pond and water garden aeration since they actually produce more circulation and water movement RAD6 Dimensions 1 1/2" diameter X 6" long Inlet 1/4" - 3/8" barb Recommended Air Flow (CFM) .4 Maximum Air Flow (CFM) 1.7 RAD12 Dimensions 1 1/2" diameter 12" long Inlet 3/8" - 1/2" barb Recommended Air Flow (CFM) .9 Maximum Air Flow (CFM) 3.5