The SMDN0090 disc neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 1/2″ dia. × 1/8″ thick, magnetized diametrical, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.006625 lbs. It can pull up to 2.79 lbs steel. And the surface field is up to 7157 gausses.