this invention relates to a nozzle having a restriction in the form of an insert comprised of a pre - metering orifice in the nozzle that causes the emerging stream to flare out and impinge on the nozzle side walls and create turbulence to flood the nozzle and achieve a predetermined spray pattern . the premetering insert is formed to provide a non - uniform orifice length and is installed immediately ahead of the nozzle to reduce the velocity of the stream without disrupting the spraying performance of the nozzle and one or both parts are made from a plastic material such as nylon .