I am replacing my old Plantronics Voyager 510 with a new Voyager 510.  I plain wore out the last device.  I work in an outdoor service environment, requiring I wear hearing protection.  This requires me to frequently remove it from service and put it in a pocket or the console of my vehicle.  It took quite a beating over the 2+ years I had it.  I bought my wife one for Christmas when a hands-free device in cars became law in this state.  It does a good job in volume adjustment and has very good clarity.  The earpiece inserts gently into the ear, making it easier to hear the person on the other end than other units that "hang" over the ear.  It also keeps the unit comfortably in place.  I appreciate the noise-canceling feature as well, which is a big plus in noisy environments.  I also like the rechargeable litheon-ion battery technology: I can use this unit for days between charges.  Unless they can improve on this headset, I hope it remains in production for a long time to come.