I'm a 32C and I had to get the medium size which fits great.  I also got the small because of my band size and that one was too small in the cups.  Wanted a moisture wicking, comfortable bra to wear during meditation and sleeping. (both very inactive things) I don't know why the description says medium support- in reality it's light support at best, but I expected that given the reviews.  It's microfiber which tends to be a moisture wicking fabric and I THINK it does a fair job of that though it hasn't been hot enough lately for me to really test that.  It is unbelievably comfortable- like wearing nothing except MORE comfortable than wearing nothing.  The problem is I could never leave the house wearing this unless I had a bulky sweater or coat on  because the slightest gust of wind can easily make my nipples pop right out and you can see them poking through any t-shirt the same way you would if there was no bra at all.  Therefore not very discreet.  I went to my buddhist temple to meditate in public service and the air conditioning made them pop out- usually not a problem with a bra on, but this bra is like wearing nothing and they got all pointy through my shirt!  How embarressing during a religious service!  I still love to use the bra in my home when not being active, but I'll never wear it outside again.