Mercury - Quicksilver Propeller Hex Nut Prop Hardware Component Hardened Brass 40140. Overview. Keeping your propeller tight and secure is essential for smooth performance, and the Mercury Marine 40140 Quicksilver Hex Nut does exactly that. Designed for Mercury and Mariner 5-15 horsepower outboards, this durable brass prop nut features precision-cut M10x1.5 threads and a built-in nylon locking insert to hold firm under vibration and load. Engineered to Mercury's factory torque standards, it ensu