Supplies: Ideal for attaching posters and notes to flipcharts, as hooks on metal surfaces, note holders on fridges, pinboard, whiteboard, etc. [not for glass magnetic boards] Small size, extremely strong adhesive force: Each neodymium magnet holds up to 20 DIN A4 sheets of paper, photos, notes on any metallic surface. Product size: 18 pieces diameter 12 x 16 mm. Premium quality: The surface of the magnets is triple coated: Nickel-copper-nickel. This protects the magnets from corrosion and significantly extends their durability. The last layer of nickel provides a smooth surface that won't scratch anything. Very handy and portable: Thanks to the easy to grip cone shape, the super magnets can be easily removed from the surface or moved at any time.