It is installed at the outlet of the osmosis water to the drain. It basically restricts (or reduces) the flow of water to the sewer. It artificially increases the pressure in the osmosis system, forcing the membrane to "work" harder, producing water more quickly and reducing reject water. The higher the number on the flow restrictor, the more water will flow into the drain. Compatible with 50, 75 and 100 GPD membranes. Easy to install. Bbagua has a customer service telephone number to resolve any questions or queries during the installation of your equipment. Bbagua is a registered trademark of the Pollet Water Group. Specialized in domestic water treatment., Manufacturer: Pollet Water Group