The Culligan D-10 water filter is a 5 micron extra-fine sediment water filter. The Culligan D-10 filter cartridge reduces extra-fine dirt, sand, sediment, silt, rust particles, and scale particles as well as chlorine taste and odor, bad taste and odor from your drinking water. The Culligan D-10 filter cartridge fits in under sink water filter systems. The Culligan D-10 is NOT recommended for use with untreated well water. The Culligan D-10 should only be used on chlorinated water supplies. The Culligan D-10 water filter is tested and certified by NSF International to NSF/ANSI Standard 42 in model US-550 and US-600.