The SMBN0640 block neodymium magnet is made from high performance N52 NdFeB, with Nickel coating. The dimension of this item is 4″ × 3″ × 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 1.62625 lbs. It can pull up to 262.1 lbs steel. And the surface field is up to 1893 gauss.