Add-It Fertilizer Injector, 1&frac12; quart capacity, &frac12; FPT inlet/outlet ASAE award-winning Add-It fertilizer injector 1 quart capacity with " FPT inlet/outlet (female pipe threads) Proportioning fertilizer injector - injection rate is constant a minimum flow rate of  GPM and 10 PSI is required to function Perfect for drip and conventional sprinkler irrigation systems