I am impressed with these!  The are stretchy enough to keep the equipment in place and they don't bunch up anywhere.  I am 160 lbs 5'8" 33" waist - I got medium and they fit really good.  Countours the butt nicely and keeps the front equipment in place and nicely displayed.  The material is very silky and a huge improvement over straight cotton briefs - no sweating at all - much like the dry-fit sports wear but not quite.  I am happy with these.