Elemental O2 Diffusers accelerate oxygen replenishment and increase water circulation when used with a high-output air pump. Their flexible lengths allow multiple configurations to suit any application. Reduced back pressure makes these diffusers less demanding on air pumps than most air stones and they're easy to clean just by rinsing under running water. The 3' and 4’ O2 Flexible Diffusers are compatible with 3/16” ID tubing.