1. The Flow Restrictor (FR) should be changed every time the Reverse Osmosis (RO) membrane is changed.2. Be sure that you order the Flow Restrictor ML size to match your reverse osmosis membrane GPD. They must match to operate at the correct efficiency. For the Flow Restrictor, the RO Membrane must be 50 Gallons Per Day.3. These are inline capillary systems that install into the drain tube itself. Just cut the 1/4-inch drain tube and push the two ends of the tube into the Flow Restrictor (FR).4. If an inline Flow Restrictor is already installed, remove the old inline Flow Restrictor and insert the new inline Flow Restrictor for better performance of RO Membrane.