This meter operates on 12, 24 or 48 VDC. LEDs show volts, amps and amp-hours on. Amp-hours can be displayed directly or as "% full". An LED indicates charging and fully charged states. Another LED indicates when charging or equalization are needed, and during low battery voltage events. Meter also records minimum and maximum voltage, number of days since last charge, days since last equalized, and total lifetime amp-hours withdrawn. The TriMetric can be located hundreds of feet away from batteries using inexpensive 4-conductor twisted-pair meter wire. A shunt is required for operation. Use the 500-A shunt on a 12 VDC inverter larger than 800 watts, or a 24 VDC inverter larger than 1600 W. Use a 1000-A 100mV shunt for systems with stacked XW inverters or where continuous current is over 300 A. The 1000A/100mV shunt has the same resistance as the 500A/50mV shunt and may be used interchangeably. Order the shunt separately. Allows for a maximum battery bank size of 2500 amp-hours. The positive lead to the TriMetric should be fused with a 1-A fuse. Flush mount or use wiremold box to mount. Made in USA. Dimensions: 4.5" x 4.75". 2-year warranty.