The SMRN0694 ring neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 3/4″ od × 1/4″ id × 3/4″ thick, magnetized diametrical, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.08 lbs. It can pull up to 20.36 lbs steel. And the surface field is up to 6574 gausses.