Calvin probably won't like this, but this brief is essentially the worlds most comfortable jock-strap.  I don't care about fashion, but with all the running and biking I do (triathlon training), these make a big difference.

The fabric on is soft, stretchy, and a bit clingy.  It has extremely flat seams.  After a 50mi bike and 10mi run, I felt nothing at all.  No, I wasn't saddle-numb.  It was the underwear.  They were soaked (of course), but even full of sweat they hadn't dug in anywhere.  This was a pretty big surprise.  Normally, water + fabric + movement yields annoyed skin or at least a pressure-point or two.

For comparison, I used to wear&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Calvin-Klein-Men-s-3-Pack-Low-Rise-Brief-Basic-Recolor/dp/B001283MZO/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Calvin Klein Men's 3 Pack Low Rise Brief Basic Recolor</a>.  I have a few of that exact type and many of similar style (all cotton).  Outside of running & biking, there isn't much difference between cotton and CK-Ones.  For road-work, though, the difference is phenomenal.

Unfortunately, I don't know how long the CK-Ones will last.  I've only been using them for a little while.  I ordered a bunch more and pray they'll last at least as long their cotton predecessors.

--

Edit: I read a review about these shrinking in the wash.  Mine have shown zero discernible shrinking.  However, they are small.  My waist is 31~32.  I bought size "M" (31-33).  They're almost too small.  If my waist was 32~33, I'd have to use size "L" instead.  If you're on the upper edge of a size range, I'd suggest trying both the recommended size and size+1 before ordering a lot of these.