The SMCN0321 cylinder neodymium magnet is made from high performance N42 NdFeB, with Nickel coating. The dimension of this item is 5/16″ dia. × 5/16″ thick, magnetized through thickness, with tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.0065 lbs. It can pull up to 5.44 lbs steel. And the surface field is up to 5903 gauss.