Unless you have a 60" waist, they work for any size waist or lack of.

Yes they come in sizes. Try the Clotilde Co. I do not have an address for them but was suggested I go on line to the catalogue. My friend is ordering some from there.

Umm, no they don't come in sizes. It is One size fits all and expands beyond belief. Here's a pic. Ignore the price. That was eeons ago. They are now up to about $5 or so.
In my most recent Clotilde catalog, they are on page 62, left side, midway. It is on the same page as the tracing paper, Shape-weights, etc. Follow Blue10moons link. That would be it.