Nancy, others will likely have better answer than I. I think
that a device has to pass FDA approval if it is being sold as
having a medical use or health benefit.

The reverse syringes you use work the same way. Except
you have to find a way for the woman to apply suction 24
hours a day (preferably) for a month. This allows the nipple to
be stretched while the underlying tissue grows. So the
marketing info says. This device is a little "thimble,"
attached by tubing to a syringe.

Margery Wilson, IBCLC