XL will fit size18comfortably right down to size12.
Lwill fit size16 to size10.
Mwill fit size10to8.
Swill Fit Size8to6
They are in a 88% polyester and 12% elastin, which stretches beautifully with the image intact, then goes back into shape when you take them off and wash them. White styles can be slightly see through.
Machine washable in cold to warm water. Do not tumble Dry.