Pentair 48 sq.ft DE Filter SMBW4048 P/N: 011555 Filtering with diatomaceous earth (D.E.) removes particles so small they are individually undetected by the human eye, but combine to decrease water clarity. 4000 Series filters remove the tiniest of contaminants, so your water truly sparkles. In addition to exceptional filtration, Pentair SMBW 4000 Series D.E. filters feature sheet molded fiberglass tanks and Noryl rotary backwash valves for long life, dependable performance and easy maintenance. Our SMBW 4000 Series Filters remove the tiniest of contaminants, so your water truly sparkles. In addition to exceptional filtration, they feature sheet molded fiberglass tanks and Noryl rotary backwash valves for long life, dependable performance and easy maintenance. Features Maximum Operating Pressure 50 psi Corrosion-resistant 20 in. diameter fiberglass filter tank for strength and durability Unique Spiro-Mite grid design provides high efficiency filtration and longer filter cycles Exclusive clamp ring design is proven to be safe, strong and reliable. It allows for quick and easy access to internal components 2 in. plumbing connections provide maximum flow