Mercury - Voltmeter 8-18V Electrical System Monitoring Black Face Brushed Bezel 79-8M6020045. OverviewThis 8-18V voltmeter gives you a straightforward look at your boat's electrical health without bouncing around every time the hull moves. The needle settles into a smooth, steady sweep, which makes it easy to spot when the battery or charging system isn't acting the way it should. Out on the water, it becomes something you check almost without thinking-just a quick glance to be sure everything's