The SMDN0085 disc neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 1/2″ dia. × 1/16″ thick with adhesive backing, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.003325 lbs. It can pull up to 3.1 lbs steel. And the surface field is up to 1601 gauss.