The SMBN0478 block neodymium magnet is made from high performance N42 NdFeB, with Nickel coating. The dimension of this item is 3/4″ × 1/2″ × 1/4″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.0254375 lbs. It can pull up to 17.16 lbs steel. And the surface field is up to 3957 gausses.