This is a mould and deckle for use in making paper. The finished paper will be approximately 3.5 x 5.5 in. The indentations are for 6 x 2 mm magnets. And the pinholes on the opposite sides are to retrieve your magnets, if desired. I bought and used these from Amazon. (That is not an affiliate link, but you're welcome to Buy Me a Coffee, please and thank you!)