After buying and trying a Blue Ant from Amazon and finding it would not fit in my ear and continually fell off my ear, I returned it.  I read the reviews about the 510 and one of the comments about wearing glasses and using this headset.  Now I have this and I love it!  With a choice of 3 ear buds, I have found one that fits and is comfortable.  I have no problem wearing this headset and my glasses.  The unit is light and comfortable, the incoming and outgoing sound is great.  I hear everyone clearly and they are impressed that I am speaking on a headset and not directly into the phone.  Highly recommend this headset.