Designed to hold the New TAOM chalk. Make sure you put the magnets in to attract not repel ;)
You will need 2 x Disc Magnets 8 x 3 mm like these
https://www.amazon.co.uk/gp/product/B074C79DJS/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1