Pentek - WP5BB20P - 20" x 4.5" Polypropylene String Wound FilterPentek String Wound Sediment Filter 20" x 4. 5" Polypropylene String Wound Filter WP5BB20P Precision wound polypropylene sediment filter with 5 micron nominal rating for high capacity whole house, well, and commercial applications 5 Micron Nominal 20" x 4. 5" Big Blue String Wound WHY IT WORKS Engineered for Higher Dirt Loading Capacity Precision Wound Pattern Polypropylene cord wound in a precise pattern around a rigid core creates greater surface