Bought a slew of these for the summer running season last year. They held up well and were virtually weightless through the summer heat. Took them through training and a marathon. I'm a good sized athletic guy at 6'1" and 205 lbs and haven't had any problems with the medium being too tight on a 34" waist. It's currently 6 months later. They're still holding up as well as the day I got them.

Note: AIR DRY ONLY--this adds to longevity on gear and avoids the tightening/stretching cycle that destroys fabrics over time.

I made the mistake of wearing Jockeys on a run today and have chafing all over. Got home, tossed every single pair of Jockeys, and am ordering spare pairs of these Adidas Briefs right now.

Very happy with these, at this price point.

****UPDATE 4/18/14****:
These have started to tear at the waistband seams on maybe 2 out of 12 pairs. Seems like the lifespan is about two years if you rotate them from a pool and take care to wash on warm and hang to dry. At this price point, that doesn't change my five star rating. I'll be replacing with the same brand. Note that the new waistband seems a little more substantial than on the ones I ordered; could be they've fixed the problem.