The SMDN0089 disc neodymium magnet is made from high-performance N52 NdFeB, with Black Nickel coating. The dimension of this item is 1/2″ dia. × 1/8″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.006625 lbs. It can pull up to 7.97 lbs steel. And the surface field is up to 3309 gausses.