Filmtec TW30-1812-24 RO Reverse Osmosis Membrane, 1-Pack Polyamide Thin-Film Composite Imported 98% Stabilized Salt Rejection (Minimum Rejection 96%) NSF/ANSI Standard 58 listed Membrane Dimensions: 11.75" Overall Length, 1.75" Diameter (Fits Standard 2" ID Membrane Housings)