On this web site, there used to be different sizes and different colors, but now there is only small size and one color.  This situation is quite terrible.

By the way, these pants are not perfect for sleeping although they got sleeping pants name, especially when they are new.  When you sleep you want your muscles to relax, the elastic waist band makes this difficult.  However after many washing and drying, the elastic waist band becomes not so tight, and it get better for sleeping.