Ceramic Coated Donut Magnet Approx 3" Diameter Donut magnet you can take to town!! 74mm dia x 14mm thick with a 30mm hole. Very strong and well pedigreed - in fact, its kin are activating pacemakers. They are of a high permeability ferrite material with a lovely light blue or white epoxy coating. Okay, we have them because there is the odd bubble, slight scratches or the word MAGNET painted in the coating which ruled them out of the medical ball, but they're fine company nonetheless. Good display bases, paper clip traps, and super for classroom demos. You will receive one magnet per order.