The SMBN0643 block neodymium magnet is made from high performance N52 NdFeB, with Nickel coating. The dimension of this item is 4″ × 4″ × 1/2″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 2.168125 lbs. It can pull up to 317.5 lbs steel. And the surface field is up to 1624 gauss.