these do give the uniboob appearance having no cups, but do a pretty good job of holding the girls in place and still.  they run close to size, band is a bit large.  if unsure, I would recommend sizing down one.
an interesting discovery with these - if u are larger than  c-cup as I am, they fit better worn backwards.  the front has a lining that doesnt stretch as much as the bra fabric does. by turning them around the 'back' will  expand to accommodate larger breasts unrestricted by that lining - more comfortable but still do the job.