The SMDN0077 disc neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 7/16″ dia. × 2/10″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.008125 lbs. It can pull up to 7.75 lbs steel. And the surface field is up to 4453 gausses.