The SMSN0744 sphere neodymium magnet is made from high-performance N42 NdFeB, with Black Nickel coating. The dimension of this item is 3/8″ diameter, with a tolerance of ±0.004″. The weight of this super strong neodymium magnet is 0.0075 lbs. It can pull up to 3.69 lbs steel. And the surface field is up to 8815 gausses.