OMG.  I had read a bunch of reviews about these sports bras and everyone said that the sizes of each bra they received were completely different.  Overall though, people were impressed with the quality, and I loved the colors and price.  I'm normally a Small (34B) but i ordered a Medium just in case.

I ordered them and they came quickly in a really nice travel zip pouch that you can reuse.  So far so good.  Colors good, construction better than I expected.  Awesome.  I put one on... PAIN!  I wore it throughout the day telling myself I just needed to get used to a sports bra. I had so much pain in my shoulders and shoulder blades.  The next day, I wear another one (I take Pilates four times a week), and it's getting a little better, but then I think maybe I'm just getting used to having elastic around my shoulders (I typically wear a strapless bra).  Then, I wear the 3rd one and I'm comfortable.

And then, remembering the reviews, I lined them all up on my bed.  The last one, the comfortable one, was about the size M that I ordered.  The other ones were S, XS, XXS.  Even though the tags all say M (and they aren't sewn in tags, they are written into the actual fabric.  I posted pictures of the size differences.  It's LAUGHABLE.  There is NO WAY these are remotely close to the same size.  There is no way that all four of these would fit the same woman comfortably.

I really liked these but had to return them.  I'm going to try to order them again, try for a Large this time.  I cannot believe how different the sizes were, hopefully this time, they're large enough to wear comfortably.