The SMBN0645 block neodymium magnet is made from high-performance N52 NdFeB, with Nickel coating. The dimension of this item is 4″ × 4″ × 2″ thick, magnetized through-thickness, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 8.675 lbs. It can pull up to 1226.5 lbs steel. And the surface field is up to 4933 gauss.