Mercury - Tachometer 6000 RPM SmartCraft Analog Gauge Gray Face 85 mm 79-8M0069460. Overview. The Mercury Tachometer (79-8M0069460) gives you clear, accurate RPM readings so you can monitor your engine's performance at all times. With a range up to 6000 RPM, it's ideal for most outboard and sterndrive applications. The gray face, clean white numerals, and glass lens offer crisp visibility in any lighting, while the standard 85 mm (3-3/8") size makes it an easy fit for your dash. Designed to inte