Very strong and solid 1/2" diameter Rare earth discs. They are a great mid-sized general purpose Neodymium magnets. Good size for magnetic therapy, science experiments or serious fridge magnets. for easy mounting. If you are looking for a stronger magnet that is the same size, take a look at our (D125DN45) rare earth neodymium magnet which is grade N45. This size and grade is also sold with a sticker on the back (D125DN45-Mount). If you are looking for the most powerful stock part in this size see D125DN50 grade N50.