Mercury - Voltmeter 8-18V Electrical System Monitoring White Face Brushed Bezel 79-8M6020069. OverviewThis 8-18V voltmeter gives you a clear look at how the boat's electrical system is holding up without the needle bouncing every time you hit a bit of chop. The sweep is slow and steady, so you can spot an odd dip or spike with a quick glance. Out on the water, it becomes a simple habit-take a look, make sure things look normal, and keep running. It's a low-key, reliable gauge that helps you stay