Awesome to help keep the glasses from steaming up, but I like the rimless better for biking in an aero position.  The frames have popped out once or twice, but are pretty easy to put back in.  My black pair lenses cracked (both sides) and I'm not sure why.  I have a wife and two year old who I blame, but either way they are going in the trash after a couple of months.  Can't beat them for the price!