This is a diameter of more than 200mm, thickness of 8mm oversized (ultra-large) round neodymium iron boron magnet, is our company according to customer requirements customized, magnet performance level is N35, nickel-plated surface, as can be seen in the picture, a 20mm coin only accounted for a very small portion of this magnet is mainly used in industry, large-scale machinery and equipment, has a very strong tensile strength, the use of the use of must be careful, or the consequences are very serious.
Check out the different shapes of large neodymium magnets: https://www.couragemagnet.com/large-neodymium-magnets/
Might be a better fit for your size;
Big flat thin round disc strong magnet 100mm dia x 3mm thick