The Culligan compatible TFM-18C Reverse Osmosis Membrane is an 18 gallon per day membrane that fits Culligan Reverse Osmosis Models H83, H82C, H8, H53 and H5. The Culligan compatible TFM-18C has O-Rings at both ends of the membrane. Features: 18 Gallons Per DayFilter Life: 2-3 yearsMade in the USA Specifications: Permeate Flow @ 65 PSI: 18 gpdAverage NaCl Rejection: 85 %Dimensions: Length 12 1/4 ", Diameter 2 1/4 "Membrane Style: Drop-in Element