Shitajikis are also known as pencil boards made of plastic or cardboard. They are usually placed beneath sheets of papers in order to write on. Due to them being used and since they are usually printed only once they're pretty hard to find especially in mint conditions. I've just started collecting Shitajikis myself so I only have a few for now.

These shitajiki have been scanned by me from my own collection and are not for sale.