Rare earth magnets detect iron particles from jewelry and coins. Rare earth magnets are made of a mixture of rare earth elements and are the strongest magnets to be found. This powerful rare earth magnet, rated 29 lbs, comes in an individual tube for convenient handling. Rare earth magnets are the ultimate product for detecting impurities in precious metals. Transline#: gt200. Size: 2x1/2x1/8. Sold Individually. Case Qty: 1 .