oakley sunglasses i.d

I had a pair of Endura sunglasses that were lovely. Really wanted Oakley M frames though. Lost them after a couple weeks. So now I have a great excuse to get some Oakleys, but probably really should'nt.

Is there any functional difference between Radar and M-frame?
or is it all fit and styling.

Radars are soo damn comfortable. This guy always has a constant supply of them going at great prices (Annoyingly he hasn't got much for sale at the moment...). I got a new pair from him rrp £220 for about £110-120