The SMBN0630 BLOCK neodymium magnet is made from high-performance N42 NdFeB, with Nickel coating. The dimension of this item is 4″ × 1/2″ × 1/4″ thick, magnetized Through Thickness, with the tolerance of ±0.004″ × ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.135625 lbs. It can pull up to 36.07 lbs of steel. And the surface field is up to 3332 gauss.