The J.E. Adams Chemical Injector is designed to meter chemicals into your water stream downline of the pressure pump under low pressure. The advantage to this is that you don't run harmful, corrosive chemicals through your pump (they can shorten the life of your pump). By applying your chemicals at low pressure, you reduce splash -- the chemical stays on the surface you're cleaning, and is allowed to work for you (less waste). This brass chem valve is a #2, and is non-adjustable. It is rated at 2 - 3 gallons per minute at 3500 - 5800 psi working pressure @ 210 degrees max. This includes a built in coupler and nipple, and clear vinyl pick-up tube with intake screen.