The 3M™ Aqua Pure™ Filter Cartridge is a sediment cartridge made from an exclusive Progressive Porosity Process that entangles and entraps larger sediment particles toward the outer diameter and progressively smaller particles toward the cartridge core. This allows even loading for maximum cartridge life. In addition, the unique square-grooved surface provides more sediment-trapping surface area than ever before. Unlike string-wound and pleated paper cartridges, the rigid, sturdy construction of 3M™ Aqua Pure™ cartridges are able to withstand variations in water pressure.