When I first installed one of these on my new Jawbone II, they were fantastic. They fit my ear canal perfectly, negating the need for the ear loop that came with it. Unfotunately after a few days they started rejecting my headset. The ear pieces would not stay on the Jawbone, and they would no longer stay firmly in my ear. I tried washing and drying them thoroughly, but that only helped for an hour or so. I am not sure what the fit problem is, but they turned out to not work for my Jawbone II and me at all.