The SMDN0047 disc neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 5/16″ dia. × 3/16″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.0039 lbs. It can pull up to 4.4 lbs steel. And the surface field is up to 5070 gausses.