I wanted a pair of clear glasses for mountain biking, because it can get pretty dark riding through the shaded forest.  I really wanted the obscenely expensive Oakley Radarlock, but I figured I'd give these reasonably-priced Tifosi a shot.  They're GREAT.  The photochromic feature is exactly what I needed--dark enough for the sunny ride to the trail, but light while I'm on the trail.  I'd give comfort a 4/5, since the earpieces and noisepiece don't sit quite as comfortable as my Oakleys.  But I'm generally happy and will probably try a few different Tifosi styles in the future.