The SMDN0240 disc neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 2 1/2″ dia. × 1/4″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.3325 lbs. It can pull up to 54.7 lbs steel. And the surface field is up to 1294 gausses.