Mercury - SC1000 Tachometer 7000 RPM SmartCraft Analog Gauge Gray Face 85 mm 79-8M0135645. Overview. The Mercury SC1000 7000 RPM Tachometer (79-8M0135645) delivers the accuracy and durability you expect from SmartCraft in a clean, modern gray-face design. It fits a standard 85 mm (3-3/8 in.) dash opening and connects directly to your Mercury SmartCraft network for instant, real-time engine RPM readings. With a glass lens, white numerals, and a sharp OEM look, it's the perfect blend of performanc