I’m sorry, my mistake, it isn’t SlimTip, it’s a cShell.
Look on the page 6 of below:
My audi give Phonak an instructions to attach to it a thing, which in Poland we discribe as “pazur” (literally: “claw” but I don’t know english term). It’s a structure which looks like an acrylic (de)formed ring, which is cut in one point and in which way obtained ends were attached to cShell custom earmold. This structure fills your auricle, which make stable position of earmold.
The con of this solution is the receiver is mounted in way that forces you/your audi have to sell it to Phonak if you want to replace/change the receiver.