I have the 350. A terrific headset even though newer headsets like those from Plantronics Voyager series outclass it now. But back when headsets were fairly new, this was an excellent choice. I have mine on right now and it gets over 8 hours of battery life with the LED light turned off. (I've used it with it on all night.) Definitely a great headset. Cost me $50 when I got on. $5 is amazing.
And palswim, you can pull off the ear hook with a little pressure and turn it over to work with your left ear. It's designed to do that and I do it all the time after one ear gets worn out with having it there.
EDIT: Whoops, I have the H500, not 350. But the only difference in it really is features. Still the same switchable ear hook and long lasting rechargeable lithium battery.