The SMBN0635 block neodymium magnet is made from high performance N42 NdFeB, with Nickel coating. The dimension of this item is 4″ × 2″ × 1/4″ thick, magnetized through thickness, with tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.541875 lbs. It can pull up to 73.33 lbs steel. And the surface field is up to 1152 gauss.