The FT400 Series displays require a frequency of at least 1 Hz in order to operate properly and the MJ and WJ Series meters typically do not provide a pulse frequency that exceeds 1 Hz. Therefore Seametrics does not recommend using the MJ or WJ units with Seametrics display units. MJ and WJ meters are intended for totalizing only and often a simple pulse counter (not provided by Seametrics) is sufficient for this task.