Uniqlo long-sleeved underwear. I only wore three pieces in rotation for one season last fall, so they're still in good condition. I think they don't sell cotton ones anymore, so how about it if you're looking for some? (It's not 100% cotton; it's 92%.) There are wrinkles from washing and storage, but there's no loss of shape or fading. Light blue Pink White 92% cotton 8% polyurethane