The string wound filter has a deep graded honeycomb structure, dense near the inside core and more open and sparse near the outside edge, forming an effective depth filtration filter, catching larger particulates first and then smaller near the center core, effectively increasing the dirt holding capacity of the filter. Significant Difference between String Wound Filter with Melt-Blown Filter. Flow Rate: String Wound Filter > Melt-Blown Filter. Dirty-holding Capacity: String Wound Filter > Melt-Blown Filter. Service Life: String Wound Filter > Melt-Blown Filter. 20″ x 4.5″ universal string wound filter cartridge fits most 20 inch big blue filter housings, as prefilter of reverse osmosis (RO) systems and whole house water filtration, as well as variety of commercial and industrial water treatment systems. Remove 99% particles, silt, sand, rust and other undissolved particles in dirty water. As the first line of defense in the filtration system, protect your water using appliances and plumbing for cleaner water, improve water quality and taste. Food grade 100% Polypropylene material, lead and BPA-free. Non-toxic, odorless, no leaching or secondary pollution. Providing a healthy, safe water-filtering experience. Food-grade material, meets NSF42 and CFR21 certification. For better water quality, recommended replace 2 or 3 times every year, depending on the quality of the original water source and application type. 3M Aqua-Pure 5618903, AP810-2. Aqua Sun International SWS-BB. Express Water WH300SCKS, WH300SCPS, WH300SCGS. ISpring FP25B, FP25BX2, WGB22B, WGB22BM, WGB32B, WGB32BM. Pentair DEV910837, DGD-5005-20, EV910837, P5-20BB. Pentek CWD-PENTEK-DGD-5005-20, DGD-5005-20, P5-20BB. Ronaqua 10S-20BB5, BBSED-20B4, 2C-20BB5. 8 x Water Filter. This item is in the category “Home & Garden\Kitchen, Dining & Bar\Small Kitchen Appliances\Water Purification\Water Filters”. The seller is “domesticwaterfilterexpert” and is located in this country: US. This item can be shipped to United States.