Because reading the reviews of other Voyager 510 owners was very helpful in making my decision, here is yet one more, with hopes I can pass the favor on.The Voyager 510 Bluetooth Headset by Plantronics does what it says, i.e., your hands are free to do anything else while you make a cell phone call...type, drive, take notes, eat a sandwich, or whatever you like doing while you're on the phone.That being said, they all do that. The best part about this one is that I can hear the other person literally loud and clear, better than via my phone itself. (Mine is a Motorola KRZR.) If that were the only feature, I would still buy this earpiece. The sound is that good. It's because, I think, the earpiece fits on the ear canal, not across the pinna, as others appear to do. Hearing is an important fact to keep in mind when buying an earpiece, wouldn't you say?True, as others have said, the on/off button is small and a wee bit awkward. But that's not worth taking off from this review. Think about it. You turn it on in the morning and off at night. It's not one of your frequently used functional buttons.The same goes for the volume buttons. They are a bit small, thus a bit awkward. It takes some push to use the on/off button, however, so working the volume toggle probably won't result in your turning your headset off accidentally. Again, once these are set you are not likely to change them. I find the volume I'm comfortable with and stick with it.The call control button is your real gearshift. It's easy to find, sitting directly over the ear piece, the center point of the unit. There is no magic to pushing it. That is, you don't have to do anything but push it...once to answer a call, once to end a call, press and hold to initiate voice dialing, press and hold to send a call you don't want to answer straight to your voice mail, or press twice to call the last number called. (Somehow its being able to remember and call the last number is intriguing).Speaking of voice dialing, next to good sound this is my favorite feature. It still fascinates me to push a button, speak a command, and complete a call to someone, all the time with my Motorola KRZR folded up and in my belt case. It's an amazing technology. If you're not careful, you can lose yourself in conversation and therefore lose mental control of your driving. On the other hand, your eyes remain forward, and you are not fumbling with flipping open your phone and fishing out numbers to push. Just be careful out there.Sound is good both ways. Those I call say they can hear me fine. I am able to test it when I dictate notes on the run, as my service allows me to replay short bits of my dictation. They sound as good as on any land line, proving good transmission.Plantronics customer service has a recorded receptionist with the most hypnotic voice I have ever heard. That makes calling them a treat. I had called looking for an automobile charger for the headset. They gave me the number for Sun Communications, who apparently are distributors for Plantronics here in the South.The clerk at Sun Communications was not very helpful. She wanted my name and phone number before she even heard what I wanted. These days, information seekers like that are not very comforting. She seemed miffed when I refused to tell her. Whatever. I went right to my question about the automobile charger. It's called a lighter adapter, and it was not in stock. It would take 10 days to order one. She would not tell me any retailers who might carry it. Just so you know, it is part no. 69520-01, per Plantronics.Not finding a lighter adapter is probably my biggest complaint about the Plantronics Voyager 510. I have one for my phone, to save me when I'm on the road and my phone battery runs down. It stands to reason that I would want one for my headset, too. The search continues.Otherwise, using this earpiece is a delight. I wear glasses, and there is no competition between my glasses and the Voyager 510. It rides well on my ear, with no wiggle at all.I could go on, but the major points are covered here. I hope this helps you make a decision.