The SMDN0244 disc neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 3″ dia. × 1/4″ thick, magnetized through thickness, with the tolerance of ±0.004″ x ±0.004″. The weight of this super strong neodymium magnet is 0.47875 lbs. It can pull up to 65 lbs steel. And the surface field is up to 1085 gausses.