When I first purchased it in 2006, I asked my favorite sales rep at the Cingular store to recommend the most comfortable one they sold. He recommended the one he was wearing, the Plantronics Explorer 320. I took his word (he hadn't led me astray yet) and bought it. I haven't regretted the decision once.I apparently am not the only one in my house that loves this little bugger. I've purchased 3 of them now, as my dog keeps getting hold of them somehow (no matter how high out of reach I seem to put them) and turning them into chew toys. But I keep coming back for the 320. It fits my ear perfectly. I can literally wear it all day with barely any discomfort. It syncs easily to every phone I've used it with. It picks up my voice just fine. I've been on the listening end, and you really wouldn't guess the speaker is using a headset.The volume on calls could stand to go a little louder, as sometimes the person I'm talking to is a quiet speaker and I'm in a noisy place. You should also know that, since it's been around a few years, it doesn't have the bells and whistles of newer Bluetooth headsets, though I personally don't need them and thus don't care.Now I'm getting ready to purchase my 4th, and odds are it will be another Explorer 320. No reason to mess with a good thing.