I purchased this headset with high hope based on other people's reviews. Anyhow, the headset did not stay in my ear. I tried it with three different adapter size and all three didn't work. the medium size worked the best, however whenever I made any face gestures (ie. smile) the headset fell out.As for performance, it did not sync really well either. I always had to re-pair the devices. My phone is the Treo 700p