The search results show postpartum incontinence/postpartum underwear and postnatal multivitamins listed as HSA/FSA-eligible.
They typically advertise maximum absorbency, disposable pull-on construction, moisture-wicking liners to keep skin dry, odor-control technology, and a discreet, underwear-like fit.
The results show size ranges from about a 24" waist up to a 64" waist and also list numeric size spans (for example, sizes 2–26).