The SMBN0401 block neodymium magnet is made from high performance N42 NdFeB, with Nickel coating. The dimension of this item is 1/4″ × 1/4″ × 1/2″ thick, magnetized Through Thickness, with tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.0085 lbs. It can pull up to 5.06 lbs steel. And the surface field is up to 6353 gausses.