The SMBN0518 block neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 1/2″ length × 1″ width × 1/4″ thick , with step OUT, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.03625 lbs. It can pull up to 21.81 lbs steel. And the surface field is up to 3559 gausses.