The SMDN0091 disc neodymium magnet is made from high-performance N42 NdFeB, with Black rubber coating. The dimension of this item is 1/2″ dia. × 1/8″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.006625 lbs. It can pull up to 6.44 lbs steel. And the surface field is up to 2952 gauss.