Polyester spun cartridges for fine sediment removal. Not washable and generally used after a pleated cartridge in duel casing systems.
They are the best cartridge to use for fine sediment removal whereas Pleated cartridges are best for course to medium sediment removal.
Duel Gradient cartridges also available for use with a single casing. These remove sediment down to 25 microns on the outer layers of the cartridge and fine sediment down to 1 microns in the inner layers.