The SMBN0634 block neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 4″ × 1″ × 1″ thick, magnetized through thickness, with tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 1.08125 lbs. It can pull up to 257.3 lbs steel. And the surface field is up to 4871 gauss.