Sonance medium round flex brackets are used to mount round 6 1/2" ceiling speakers. The Sonance web site says these work with all Sonance Visual Performance Series and Original Series speakers.
These are sold only in boxes of 10 (5 pairs), which sell for $160. I was using these in a new house build and needed 6 pairs so had to buy two sets; these are extras that I didn't need. They are brand new.
I have them in Green Valley but can meet up with a buyer in Tucson / Marana / Oro Valley.