Explanation is in the thread.

Just headphones. Except they 'bond' with the ARC soundbar.  BIZARRE. 

They only work with the Arc. Otherwise they are just another pair of lossy compressed audio Bluetooth headphones. Major missed opportunity. To say I’m disappointed would be an understatement. 

Such a shame, they have really dropped the ball on this one. First of they make a dreadful app somehow even worse, then bring out an overpriced pair off earphones that really do not have a Sonos message of inter operability do not connect into the Sonos economy system unless you have the Arc and are just over priced headphones

Strike two!