Quicksilver - Aluminum Prop Nut Anode Fits Select Mercury Propellers and Outboard Engines 2-1/2" Diameter 809670T. Overview. Every seasoned boater knows that protection is just as important as power. The Quicksilver Aluminum Prop Nut Anode (Part Number 809670T) is that quiet defender working beneath the surface-keeping your Mercury or MerCruiser drivetrain safe from corrosion so you can focus on the moments that matter. Whether you're spending the day fishing, exploring, or cruising open water,