Pack of 20. 8mm diameter x 2mm thick. +/-0.1mm tolerance. Each magnet's north and south pole are on opposite 8mm diameter faces. Coated with three layers of nickel, copper and nickel to reduce corrosion and provide a smooth finish. Each magnet can support a steel weight of up to 1kg vertically from the magnetic face when in flush contact with a mild steel surface. Excellent resistance to demagnetisation.