Material: neodymium and plastic shell; Coating: Nickel Super strong and can hold up to 16 pieces of 20 lb of paper Small magnets, easy to handle Applications: office, advertising, education and other purposes Super Strong Magnets Made Of Neodymium Material Color: Random Dimensions: diameter 11 * 17mm high Magnetic mass: diameter 6 X thickness 3mm Degree: N35 Package included 14 X Color magnetic thumbtack Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.