The REDARC Dual Voltage 2-1/16 Gauge monitors battery systems mounted in 4WDs, campers, caravans, motorhomes and other similar types of vehicles. The dual gauge allows you to see the charging performance of both your main and auxiliary batteries via its LCD/LED display. If there is a system failure, the gauge reading will drop as the battery discharges. If there is an overcharge situation, the reading will climb above the normal zone. The G52-VVA gauge also has pre-set alerts created to monitor battery health and will change the gauge's backlight to either amber or red. The G52-VVA gauge requires a 2.05 hole for mounting. REDARC offers several mounting solutions including a 2 black plastic mounting cup (GH-CUP) and a one (GH-MP1) gauge mounting panel. Features of the gauge include satin chrome bezel and 13 backlight color options to choose from. It also has multiple alert levels with amber or red backlight and an audible beep when voltage drops below 11V or exceeds 16V. If using more than one REDARC gauge, you can engage a communication link to connect gauges and change the backlight color simultaneously. Purchase the REDARC Hall Effect Current Sensor (GS-AMPS) to equip your gauge with an optional 100A rated current display, which monitors the amount of current to or from your main or auxiliary battery.. . . . .