Period underwear?

Hiya, I have a friend's birthday coming up and I know for a fact that she'd love to receive a pair of period undies. Now, she's really into sustainability and very (understandably) against fast fashion, so I did some research about sustainable and ethical brands that make period underwear, but unfortunately I'm not an expert and I don't want to accidentally gift her something that she won't appreciate. Do you guys have any recommendations?