The band around the rib cage has a stiff material along with the elastic. It is a very odd decision in terms of construction, because it means a stiff maybe even sharp, material is scratching my torso as I move around. I also didn't really like the way the cups fit, the weight was centered too low. I didn't genuinely exercise in the bra, though, so I don't know if it prevented bounce well. Another Frey sport bra I have also has the same sort of intensely reinforced stitching all along the edges, including on the straps. This means the part of the strap that's pressing into my skin is the scratchy stitching, even though the material of the straps is soft, (but that's not where the pressure is).