This highly efficient filter is an excellent upgrade to your existing FM-300 dust extractor. Pleated cartridge filters are far more efficient than even needlefelt filter bags. This one is manufacturer rated at 1 micron. It will also suit many other brands of 1 hp dust extractors. The unit is cleaned by rotating the handles several times. Doing this rotates a rubber beater inside that removes settled dust from the pleats. Unit needs to be used with plastic collection bags in place of cloth bags. These are available in packs of ten in the relevant sizes for each machine. Pleated cartridges not only provide vastly enhanced micron filtration, the pleating also increases the surface area by over 700%. This in turn also increases the CFM rate.