It collects iron powder that has been trapped in engine oil and reduces internal scratches
Strong 5000 Gauss Most Powerful Neodymium Magnets in Existing Permanent Magnets, Aluminum Hard Anodized Finish.
Compatible models are here.
http://www.trust-power.com/products/oils/greddy-%E3%83%8D%E3%82%AA%E3%82%B8%E3%A0%E3%83%9E%E3%82%B0%E3%83%89%E3%83%AC%E3%E3%E3%E3%B3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%E3%83%9 C%E3%83%AB%E3%83%88/