The SMRN0709 ring neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 1″ od × 1/4″ id × 1″ thick, magnetized diametrical, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.199375 lbs. It can pull up to 40.44 lbs steel. And the surface field is up to 6909 gausses.