The size guide, which I carefully followed, recommended an XS, which was too tight all over for my comfort level. I could hardly get it on. So I switched to a Small, which feels better around the band and cup. I find the adjustment system at the back clever, as it allows some more support, without adding thick snap and hook attachments (I go from yoga to pilates to jogging in a day and was looking for something supportive enough, yet flexible and comfortable for all three sports). And I found it ! The one improvement I would like to suggest is to shorten the “over the shoulder” bands. Right now in order to tighten it enough, the plastic slider has reached it maximum (middle of the bra), a little more leeway would make it perfect. Thank you for this great product.