The SMBN0451 block neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 1/2″ × 1/2″ × 3/8″ thick, magnetized Through Thickness, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.025625 lbs. It can pull up to 16.55 lbs steel. And the surface field is up to 5286 gausses.