Resound Multimic with Costco 5.0s?

I have the Costco Kirkland 5.0 HAs and have been told they are compatible with the Resound Multimic.
Can anyone confirm that?
If you have that combination could you please comment on how you like it?
The Resound Multimic can be bought on Amazon for $300.

I asked at my Costco in San Antonio, TX and was told that the Multi Mic could be special ordered at $266 and the Phone Clip+ at $209 - that they don’t carry it in stock.