The SMDN0033 disc neodymium magnet is made from high-performance N42 NdFeB, with Black Rubber coating. The dimension of this item is 1/4″ dia. × 1/8″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.0016625 lbs. It can pull up to 2.3 lbs steel. And the surface field is up to 4667 gausses.