I purchased a Big Board and a cover to go with it.
The "batting" is just a piece of about 1/8 inch thick craft polyester
The cover is made of a heavy (ivory colored) cotton fabric that resembles denim, duck, or twill. It is elasticized around the edges.
It was also cut VERY skimpily and I use elastic strips pinned to the edges and going underneath the ironing board to help hold it in place.
The fabric shrinks - a lot - every time it is washed, so I have to put it back on the board when it is still quite damp for it to be almost big enough.
Other than the size issue, I've found the two layers (1/8 inch craft polyester and cotton cover) to be very adequate for all types of ironing and pressing.
I prefer to be able to remove the cover so I can wash it now and then over having something stapled or nailed to the board.