Seemingly, the CK One Cotton Stretch line is replacing Calvin Klein's 365 underwear.  It's sort of baffling that Calvin Klein phases out its superior underwear lines (just like sizing isn't consistent from line to line!) because I'm not entirely sure that this is an adequate replacement.

The stretch cotton briefs, in my opinion, are only ok.  The fabric feels nice and somewhat thin, which I like because it keeps me cool.

They're generally comfortable, too.  But I've found that, the longer I wear them, the more uncomfortable they get in the bottom back.  I'm not sure whether that's because the elastic around the back of the legs stretches out from activity, but the feeling of those areas loosening and getting shifty can be really irritating.

The cut is alright, too.  It seems to look a little different on me than some of the photos.

I'd say that, if you're adventurous and into trying new underwear, give these a try.  My only reservation is that these briefs may become uncomfortable for you as the day goes on just like they do for me.