These heavy-duty magnetic bulldog clips are commonly found in warehouses and restaurants holding inventories or bills as each magnet will hold an astonishing 6kg of paper or other material. The Neodymium magnets are sunken in to a steel shell meaning that the north pole is on the centre of the magnetic face and the south pole is on the outer edge around it. The steel pot increases the adhesive force of the magnets giving them an incredible hold for their size.