My Audi said I should order Prowax miniFit for the Oticon Alta. That didn’t work. Here’s why…
The (tenny/tiny) prowax miniFit wax filters do fit directly on the end of the miniFit speaker. However, in this case with a custom mold, the larger Prowax filter is used to fit onto the micro-mold, not onto the speaker (see photos below). When you wear custom micro-molds you are likely wearing two wax filters per ear (one Prowax miniFit on the end of the speaker, and a second larger Prowax filter on the outside of the micro-mold).
Note there are many other >>Oticon wax filters<< so these specific wax filters may not apply to your model hearing aid (HA).
Sorry, the pictures got lost.