The SMSN0742 sphere neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 5/16″ diameter, with the tolerance of ±0.004″. The weight of this super strong neodymium magnet is 0.0043125 lbs. It can pull up to 2.52 lbs steel. And the surface field is up to 8815 gausses.