Strong Countersunk Ring Magnets 20×3/5/8/10mm Hole 5mm Rare Earth Neodymium

N52 Magnets Countersunk Various 20×3/5/8/10mm Hobby DIY Industrial Magnet Strong. Care should be used when handling two magnets as they can pull together with such force that pieces of the magnets can splinter off and cause injury.

eBay