The First Line Membrane Housing series includes high-performance fiberglass reinforced plastic (FRP) pressure vessels designed to house standard reverse osmosis membranes in commercial and light industrial water treatment systems. Built for durability and long service life, these housings provide excellent resistance to corrosion, chemicals, and pressure fatigue. First Line membrane housings are available in 4040 and 8040 sizes, supporting single and multi-element configurations with end port or side port designs.