Mercury - Speedometer 45 MPH Boat Speed Monitoring Black Face Chrome Bezel 79-8M6020003. OverviewThis 45-MPH speedometer gives you a straight, steady read on how the boat's moving. The needle doesn't twitch when you hit a little chop-it eases into place and stays there. Out on the water, it feels like one of those gauges you check without thinking: glance, get your number, and keep going. It's simple, clean, and does exactly what you need it to do.. Key Features • 45-MPH Scale - Lays out speed o