I was VERY happy when I saw that an adapter like this existed as when I upgraded my cell phone last year the 2.5mm earsets I had were useless in the new phones 3.5mm jack. I ordered a 2.5mm to 3.5mm adapter but it would not work on my phone and the company even sent another but it must be something about the phone itself (HTC Incredible) but proper sets work fine. I found this and decided to give it a try as I liked the idea of using the earset over only one ear and able to make use of the quality and comfort I had in the phone earset.