Pentair Pentek WP Series Cartridges are manufactured from a durable polypropylene string that is wound around a rigid polypropylene core. They are premium string wound solution to reduce fine sediment, including sand, silt, rust and scale particles. WP Series Cartridges by Pentek are wound in a precise pattern around the core, providing greater surface area. The result is higher dirt loading capacity and greater efficiency than standard wound cartridges. These string-wound cartridges are capable of withstanding temperatures up to 165°F (73.9°C), and will accommodate flow rates between 7 and 10 GPM with minimal pressure drop. WP Series Cartridges are suitable for a wide variety of sediment filtration applications, including municipal and well water as well as many industrial fluids.