Hanky Panky
Not a plastic-free brand in any sense - the product it is famous for is built from synthetic stretch lace. The signature Signature Lace styles are a 100% nylon body with a nylon/spandex trim, and only the small crotch lining is cotton. The appeal is the soft, stretchy, no-VPL nylon lace, which is precisely the material a plastic-free shopper is trying to avoid against the skin. USA-made and durable, but synthetic by design.
How clear are their specs?
Fiber content is listed cleanly and separately for body, trim, and crotch lining on each product page (e.g. body 100% nylon, trim 90% nylon / 10% spandex, crotch lining 100% Supima cotton).
Products to avoid
Documented so you know what to skip — each still has a full breakdown and sources.