iSpring 1M-50PK 1-Micron 10-Inch by 2.5-Inch Sediment Filter, 50-Pack 2.5-Inch by 10-Inch Made of 100-Percent Melt-Blown Polypropylene, 4-layer filtration 1 Micron Fits 10-Inch filter housings Tested by independent third-party to meet NSF/ANSI Standard