The SMBN0399 block neodymium magnet is made from high performance N52 NdFeB, with Nickel coating. The dimension of this item is 1/4″ × 1/4″ × 1/4″ thick, magnetized through thickness, with tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.00423125 lbs. It can pull up to 5.26 lbs steel. And the surface field is up to 6451 gausses.