Easy and effective method of checking the flow output of nozzles. No need for a jug or a stop watch. Simply set the dial at the base of the FlowCheck to the nozzle size being tested, for example here an 04, red. Hang the FlowCheck(s) on the boom under the nozzle (can be a single one or a number spread across the boom), turn on the pump, set the pressure to 3 bar and the FlowCheck will indicate the output of the nozzle in seconds, and without getting wet.