Tier1 US-UF-100-RM 4-Stage Ultra-Filtration Hollow Fiber Drinking Water System Replacement Membrane is a replacement membrane for the US-UF-100 sytem. The replacement membrane is designed to reduce total dissolved solids commonly found in drinking water. This product provides high-quality drinking water at a great price. It is recommended that you replace the membrane every 12 months, or 1,500 gallons, for a cleaner, better tasting drinking water. Order today for fast shipping!