An engine is made of various parts working together to create power. Under normal operating conditions, these parts sometimes come into contact with one another, which wears down the surfaces. When the engine is running, oil is directed to the friction areas and a thin film lubricates and cushions the contact points. If an engine hasn't been started for a long time, the oil will have receded from many surface areas, and in the seconds it takes for the oiling system to relubricate at startup, metal-to-metal contact can occur. As slight as this friction is, it's still enough to break loose microscopic slivers of metal and introduce them into the oiling system. It's the oil filter's job to keep these particles out of circulation.
But debris can sometimes tear through the oil filter and cause wear or damage to the engine. To help prevent this, B&B International has designed a slick device called the FilterMag that attaches easily to the outside of the oil filter. The FilterMag uses a powerful magnet to trap harmful particles against the inner wall of the filter and keep them out of the flow of oil. According to a study conducted by Cummins Engine, particles smaller than 10 microns generate 3.5 times more wear than particles larger than 10 microns. The FilterMag traps steel particles as small as 2 microns and keeps them from harming your engine.
If you're curious about what happens inside your oil filter, Powerhouse Products offers a special cutting tool for extracting the internals. We used one after testing the FilterMag on our daily driver and confirmed that the Neodymium magnets do attract small particles as advertised. While any engine can get along without a FilterMag, just think of it as inexpensive protection.