Avanti Membrane Technology Stage 1 Sediment Filter for under-sink RO filtraiton drinking water system - NSF certified, 5 micron, 10 inch, 2.5" OD X 9-7/8" L (SED-1025-05) * 1st stage premium polypropylene depth filter Reduces sand, silt, sediment, rust and suspended particles from the water Fits most industry standard 10-Inch under-sink filter housings 5 micron particle retention size