Cascade internal fitting refers to a type of connection system used in the installation of water treatment systems, specifically in reverse osmosis (RO) systems. The fitting connects the RO membrane housing to the RO pump and controls the flow of water through the system. Cascade fittings are designed to prevent leaks and improve the overall efficiency of the RO system. They are typically made from high-quality materials such as stainless steel or brass and are resistant to corrosion and other types of damage that can occur over time. The internal design of a cascade fitting includes a series of small channels and pressure points that help regulate the flow of water through the system. The fittings are also designed to be easy to install and maintain, with most models requiring only a few simple tools for assembly.