Radial Ring Magnets - Neodymium Magnets - SuperMagnetMan
Super Strong Neodymium Cup Magnet 1.5" Countersunk Permanent Magnet, The World's Strongest & Most Powerful Rare Earth Magnets by Applied Magnets with Screws 4Pc: Amazon.com: Industrial & Scientific
N42 Neodymium Diametrically Magnetised Cylindrical Disc Magnet - 20mm dia x 20mm thick
Neodymium Magnets Rare Earth Disk Ring Super Strong Craft Various Strengths | eBay