The Pentek ECP20-BB Sediment Water Filter media is pleated around a rugged polypropylene core for additional strength with end caps and gasket fused together for a unified and reliable whole. This filter is a great deal with more surface area than most competitive cartridges (18 square feet of media compared to 13.5 square feet in other brands). It s easy to install with a long-lasting filter life. Recommended for chlorinated water supplies only.