The 1⅛″ FM Nozzle Inserts measure from 118-324 GPM.
Nozzle Inserts obtain flow-rates lower than what the 2.5″ orifice on the HM2H can accurately measure. They are required for flow-rates lower than 533 GPM.
FM Nozzle Inserts have achieved Factory Mutual approval for accurate flow rates when used with the 2½″ Hose Monster (HM2H).