Dow Filmtec TW30-2521 Commercial Reverse Osmosis Membrane Dow Filmtec membranes deliver savings by providing the industry's longest lasting and most reliable performance Dow Filmtec membranes are available in a variety of sizes to meet a range of space requirements Dow Filmtec membranes provide the highest performance quality and lowest energy costs Free Chlorine Tolerance: &lt;0.1 ppm