Great lululemon dupe. I am a 36B and ordered a medium, I could have gone with a small though for a little more support. It is, as advertised, light support but I did run and do plyometrics without an issue.

Update: ordered a small, and while it does obviously give extra support, the strap slightly pulls up in the back which is a bit uncomfortably for me. Im 59 so if shorter maybe this won't happen to you! Ill stick with medium.