Heba is supposed to be a filter as well as a diffuser but its not free and its advertised as good for 15 smokes.
Why not use the regular sized "bent elbow" plastic straws? Two for a mini, 3 for a junior and 4 for large hookah.
You cut them according to bowl size and not only is it practically free, you can lengthen the size of the shaft, which is often the problem in some minis which force you to put water up so high.
I'll show the Heba, and the straws in photos. The straws can be longer if you want.