3
1. They keep them up and tight.
2. when they sag they hurt.
3. they don't swing throwing sweat every where.
4. big tits just hanging are gross
5. old tits sag and look grosser
6. small tits don't need bras any way.
7. prevents nipples from getting sore and chafed.
8. puts balance back on lower back and hips(for big breasts) making walking up right easier.