Mercury - Tachometer Gauge 6K Engine Speed Monitoring Black Face Brushed Bezel 79-8M6020037. OverviewThis 6,000-RPM tachometer gives you a steady, honest read on what the engine's doing, even when the boat's moving around a bit. The needle settles quickly, so you don't get that jittery look that makes you second-guess the throttle. Out on the water, it feels predictable-roll into the power, back off, hit some chop, and the gauge keeps its cool. It's the kind of instrument you stop thinking about