The SMDN0243 disc neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 3″ dia. × 1/8″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.239375 lbs. It can pull up to 40.5 lbs steel. And the surface field is up to 548 gausses.