Plantronics is the only company that "gets it" about bluetooth volume. Some of us need to use a bluetooth in a noisy environment, like around machinery, and this is the only one I've ever tried that actually delivers the volume. HOORAY! My son runs a furniture store and uses these for his delivery guys. He swears by them.But it's even better than that. They MUST have tweaked something since I bought my last 510, because wind noise problems seem to be a thing of the past! Previously, a 1-knot wind would render me inaudible to the guy I was speaking to... as in, fuggedaboudit. I don't have that problem with this one. WOW!On the flip side, the charger jack is proprietary instead of USB, but that can be excused due to the age of the product. When the 510 was designed, the industry tried to make their profit by selling about 2,000 different kinds of incompatible chargers. USB has replaced that.Importantly, however, it still seems to glitch. Previously, I had FIVE of these things simply grow weak over a 2- to 3-month period and finally die. FIVE!! I don't use them in crazy places, just walking between offices, driving in my car, etc. To their credit, Plantronics replaced ALL OF THEM UNDER WARRANTY. WOW. That is SERVICE. But a functioning product would have been even better. I hope the recent glitches are temporary. I've had this for about a month.Finally, it is clear no one who designed these ever actually USED them, because the product ID requires a microscope to read, if you need it for warranty purposes.