Many thermal sets use cotton/polyester blends (often shown as 60% cotton / 40% polyester), while others use polyester/spandex mixes (commonly 90% polyester / 10% spandex).
Care labels commonly recommend machine wash and tumble dry.
Yes. They're designed to serve as base layers that provide warmth without excessive bulk so you can comfortably wear daytime clothes or pajamas over them.
Listings commonly show women's sizes from petite to plus, with ranges such as XS–3X.
Features include fleece lining and moisture-wicking fibers or fabric constructions intended to retain warmth while reducing sweat.
Comfort details include elastic waistbands, tapered legs for easier layering, and tagless or smooth seams to reduce irritation.