I bought this for myself since most women's sleep pants have really annoying bright colors and cartoonish patterns. I wear a size 6 and the small fit perfectly. It's not flannel, but the long-sleeved t-shirt is thick enough to work in winter. The sleep pants are cotton and lightweight, which is what I prefer - this set and a pair of socks are now my uniform for reading on a winter's night. The navy and subdued plaid pants pattern are so much more tasteful than what you normally find for women.