I have tried more than 12 different bluetooth headsets.  The SBH-500 is the best ever.  Outstanding call quality - never a complaint from the other party.  Outstanding bass response, high frequency and stereo separation.  It sometimes loses the bluetooth connection with my Iphone but I think the problem is the Iphone because it does that with most of the other headsets I tested.  I will buy a second SBH-500 as a backup.