I have owned this 510 for almost four years and have worn it nearly eight hours every day.  I have been very satisfied.  The cons for this ear piece are it does not block wind and background noise very well.  My ear buds are getting very loose after four years, so I am ordering another set of those.  I also ordered a new pro plus headset after watching the product demo in the wind tunnel.  Very convincing.  I will rate the new headset after I try it out.  At any rate, you can't go wrong with  the 510.