Neodymium is a 'rare earth' magnet material and they have the greatest pulling force of all permanent magnets. This listing is for a pack of 50 6mm x 2mm round Neodymium magnets with a 0.2KG pull WARNING: NOT SUITABLE FOR YOUNG CHILDREN. These are very powerful magnets, and should be handled carefully, and kept away from pacemakers, televisions, credit cards etc.