Just a bra that covers and tries to hold them down.
However the entire breast area still moves up and down
on the chest while running  (I'm a 32 B people!).  I
tried a small and thought - if this had adjustable straps then it
would be better... darn.  Returned it.  Needs more spandex in it
lots more!  Looks pretty - if that's what you're going for...
but I'm a serious runner.