Express end cap Standard Flow 10mmFits all 1 inch boom lines with 10mm port size for nozzle body stems which is industry standard. Conventional boom designs trap air in the boom causing a delay from the close signal to when spray actually stops. Pentair's Hypro Express nozzle body end caps include a passive feature that eliminates the trapped air by allowing the air to escape through the nozzle body. When the boom is completely filled with liquid, the nozzle body's diaphragm check