RQ-HM057AD-H HOUR METER:Tracking the total running time of the equipment in Real-time,the initial data is 0,the TOT range is 0-99999H,0.1/1H accuracy, cannot be reset, but when the maximum value is exceeded,hour meter will reset automatically . MAINTENANCE TIMING MODE:The default value of maintenance reminder is 50H,Can be used to change the oil. DATA STORAGE:When the external power supply is turned off, the data will be stored and accumulated data automatically . WIDE APPLICATION:Suitable for DC power supply equipment: 6V 12V 24V 36V 48V Wide voltage range: DC 5-60 volts;DC voltage compatible.Suitable for most types of zero-turn lawn mowers; also suitable for other DC power supply equipment.