The Pentair Pentek TLC-50 is a residential reverse osmosis membrane built on an industry-leading thin layer composite (TLC) design that delivers high-quality water across a broad range of water chemistries. It carries a 96 percent nominal rejection rate and reduces total dissolved solids for cleaner, better-tasting drinking water. Each membrane ships 100 percent dry to maximize shelf life and is tested to the factory's strict performance requirements before shipment. The TLC series is Tested and Certified by NSF International against NSF/ANSI Standard 58 for material safety and the reduction of arsenic, barium, cadmium, hexavalent and trivalent chromium, copper, turbidity, fluoride, lead, radium 226/228, selenium and TDS. Nominal performance of 50 GPD (189 LPD) is rated on a 500 ppm softened tap feed at 65 psig, 77 degrees F and 15 percent recovery after 24 hours. With standard dimensions of 11.75 inches in length and 1.79 inches in diameter, the TLC-50 fits commonly available residential RO housings. Operational limits are a maximum 125 psi, maximum 120 degrees F, pH 4 to 11, and 0.1 ppm free chlorine. Replace the membrane when you notice a decline in production or TDS reduction, since performance varies with incoming water quality.