LiquaGen Pack of 25 Reverse Osmosis Sediment Block Filters (2.75" x 9.75") Polypropplyene Sediment, layers Structure Nominal Micron Rating Reduces Fine Sediment, Sand, Silt, Rust and Scale Suitable for Municipal and Well Water Applications, Operation Temperature: 40F to 145F(4.4C to 62.8C) Filter Media: Polypropylene If you have any questions please feel free to contact us on 1(310) 745 6939. We request that the customer works with us in good faith to resolve any issues