There are three models with a pump outlet from 100, 200 (2 x 100) and 400 (2 x 200) l/h, on which the smallest model has one and the two larger ones both have two individually adjustable air outlets. And they come equipped with one or two EHEIM diffusors.The air flow can be regulated at each outlet on the pump and also on each diffusor. This allows you to set your own individual bubble effect.- By the way: Vibration dampening rubber edgings contribute to the pump’s quiet operation. The air pump stays still and doesn’t “wander about”. Or you can hang it vertically on the aquarium glass. Specially for this there is a hook.Advantages of the EHEIM air pump-3 models to fit all common aquarium sizes-Very quiet operation-Long service life, best quality-Airflow adjustable at each air outlet on the device-Additional adjustment of the air flow and bubble effect using the diffusor-Completely equipped with- Diffusor: air pump 100 = 1x air pump 200, 400 je 2x- Airline: air pump 100 = 1 m air pump 200, 400 je 2 m(Diffusor also available as a separate accessory)-Rubber suction pads to dampen vibration-Hook for hanging vertically-Diffusor with replaceable pad