These keychain magnets offer strong neodymium magnet power in handy keychains. They are perfect for jewelers, recyclers, coin dealers, or anyone that needs a convenient, easy-to-carry magnet to test for iron, nickel, or cobalt content. Featuring a durable N52 neodymium magnet housed in a plated metal shell, each keychain magnet has a pull force of over 3 pounds. Determine if jewelry is silver or gold plated by testing if ferrous metals are used as the base metal (excluding some nickel alloys). If a magnet responds to jewelry, it is not fine silver or anything near pure gold. The same is also true of brass and bronze antiques, many are just brass plating over steel or iron. This strong magnet can also be used to determine polished aluminum from stainless steel in most cases, and is very handy for testing industrial metals for recycling. The keychain magnet features a powerful 12mm N52 grade (3 lbs minimum pull strength) neodymium rare earth magnet encased in a plated steel housing for durability and comes with a stainless steel split ring. Product Specifications Type: Neodymium Magnet Keychain Material: N52 Neodymium Dimensions: 0.47 inches wide at its widest point x 1.57 inches long (12 x 40 mm) Weight 0.6 oz (18 g)