This protects the membrane from the back flow pressure of the tank, maintaining maximum osmotic pressure at all times. Great for low pressure applications. • Increases product water purity • Increases pressure and flow to the faucet • Saves up to 3/4 of inlet water • Up to 30% more tank pressure • Faster tank refill recovery • Increases filter and membrane life • Requires no electricity • Mounting Clip Supplied. Order the optional auto shut off valve that triggers at 90 percent rather than the standard 66 percent of tank pressure versus incoming line pressure. While the permeate pump works fine with a standard 66 percent auto shut off valve, the 90 percent valve increases storage capacity of the tank and increases initial pressure from the faucet. Will not install on most manifold systems such as Hydtrotech and Water Factory.