I bought the pad and cover from Big Board -
the pad seems to be about a 1/8 inch firm polyester craft type batting/filling
the top is a cotton twill with an elastic cord - it would have been better if it had been cut at least three inches longer.
it shrinks when I wash it - even in cold water - so I have to put it back on the board when it's still fairy damp to make it fit
I pin three strips of elastic under the board to help keep the top from popping off
i do like to be able to wash the cover.