here 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-resistant rubber feet also contribute to smooth run-ning. 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.