These Cartridges are manufactured from a durable polypropylene cord that is wound around a rigid polypropylene core. They are an economical solution to reduce fine sediment, including sand, silt, rust and scale particles. These string-wound cartridges are capable of withstanding temperatures up to 165 degrees F, and will accommodate flow rates between 7 and 10 GPM with minimal pressure drop. 20 Micron: Normal Household usage