The SMRN0685 ring neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 5/8″ od × 1/8″ id × 5/8″ thick, magnetized diametrical, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.049875 lbs. It can pull up to 16.26 lbs steel. And the surface field is up to 6937 gausses.