The Kamui Chalk Shark uses two powerful earth neodymium magnets, which are among the most powerful magnets available. One magnet is inserted into the leather disc on the metal pocket clip and another is installed in the bottom section of the vinyl chalk holder. This chalker also includes a vinyl cover that will keep chalk residue from getting all over everything when not in use. Specifications Kamui Material: 6 sided Vinyl Hexagonal Chalk Holder (for Kamui ROKU) with Metal Clip and Leather Base (chalk not included).