Pack of 2 - Big Blue Sediment Water Filters | 4.5&rdquo; x 20&rdquo; | 5 Micron Applications Food and beverages Reverse Osmosis Pre filtration Oil and gas Fine chemicals Electronics Metal finishing Pulp and paper Using 100% food grade Polypropylene (PP) as material, the filter cartridge contains no wetting agents, solvents, antistatic agents or binders. The surface layer of the filter cartridge is designed to be low density to assure the high dirt-holding capability, while the inner layer is higher density to keep the accurate micron rate to stop small particles. Then density type is 30% higher filtration effect then the general type.