Mercury - Omega Gauge Nut 85 mm 11-8M0204697. Overview. The Mercury Omega Gauge Nut (11-8M0204697) is the correct OEM nut for securing large 85 mm (3-3/8") Mercury SmartCraft gauges and MercMonitors. It threads smoothly onto the back of your Omega-style gauge, keeping it tight, secure, and free of vibration.. It's built from durable, marine-grade material that won't crack or strip, giving you a snug fit that lasts season after season.. Key Features. Fits 85 mm (3-3/8") Mercury SmartCraft and Omega gauges. OEM replacement nut - same part used in factory installations. Marine-grade plastic resists corrosion, vibration, and UV damage. Threads cleanly for a solid, rattle-free fit. Designed to hold large gauges tight without distortion. Compatibility. Fits: Mercury 85 mm (3-3/8") Omega-style gauges and MercMonitors. Performance & Practical Benefits. This nut locks your gauge in place so it doesn't twist or shift while running. It's a small but critical part for a clean, professional install