This PJ set is extremely comfortable, I only wore it a couple times and then decided I was more of an old shirt PJ gal. It is a sort of jersey material which makes it stretchy and breathable. And the lace accents are super cute. It's one size, but for reference it fit me on the looser size and I'm a size small in most things. (Not baggy, just not form fitting which I found was nice for PJs)