I loved these until, after I had them for about a month, I discovered that they had broken, exactly where others reported them broken, near the right earphone. The bluetooth worked well after I changed the settings on my Centro a bit, and they were reasonably comfortable on the 7-mile jogs I went on. I have no clue why they broke; there were no symptoms of weakness that I noticed. Now they still work, though I would have  to hold the right earpiece to my ear.