The Pentek BP-420-10 20 Bag Filter is made of a glazed polypropylene felt that is compatible with many corrosive fluids, including acids, alkalis, oils, organic solvents and microorganisms. This felt, which is created by needle-punching two layers of synthetic fibers together, has a higher solids loading capability than similar mesh fabrics. The outermost surface fibers of this filter media are then glazed to forge a bond that reduces migration possibilities. This is a 20 bag filter with a micron rating of 10.