Hydro Flow? by Netafim Woodpecker Pressure compensating junior dripper with built-in check valve and barbed outlet. These drippers adjust themselves automatically to the system pressure resulting in a watering uniformity, even on slopes. Since all water is delivered directly to the container, there is no run-off-saving water, fertilizer and energy. These drippers are a great solution for soilless substrates and hydroponic applications because each planter or rock wool cube receives an equal and precise amount of water nutrients. These drippers can be used in conjunction with dripper stakes and spray stakes. Recommended operating Pressure Range: 14.5 - 45 psi.