The SMBN0644 block neodymium magnet is made from high performance N52 NdFeB, with Nickel coating. The dimension of this item is 4″ × 4″ × 1″ thick, magnetized through thickness, with tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 4.3375 lbs. It can pull up to 833.2 lbs steel. And the surface field is up to 3032 gauss.