I've been using Smith eyewear for a number of years and rarely ever thought about it. I guess that means the equipment is doing its job if you don't even notice or think about it. For 4200+ miles the Smith Theory slider style glasses were comfortably on my face. Rarely did I ride without them and rarely did I notice them. From burning sunlight to hazy overcast skies, the glasses and the three interchangeable lenses just performed, not fogging, not sliding, not getting in the way.