Mercury - Tachometer 8000 RPM SmartCraft Analog Gauge Gray Face 85 mm 79-8M0069461. Overview. The Mercury Tachometer (79-8M0069461) gives you precise RPM readings up to 8000 RPM, making it ideal for performance-focused Mercury engines. The gray face, bold white numerals, and glass lens provide sharp visibility in all lighting conditions, while the standard 85 mm (3-3/8") size makes installation simple. Designed for SmartCraft-capable systems, this tachometer delivers smooth, accurate data in rea