Mercury - Magnesium Bracket Anode Corrosion Protection Magnesium 8M0179705. Overview. Anyone who spends time on freshwater knows that corrosion doesn't show up overnight. It sneaks in slowly-season after season-unless you're ahead of it with the right protection. That's why the magnesium bracket anode is one of those small, quiet heroes on your Mercury V12. You install it, forget about it, and it just works. With Mercury Marine part 8M0179705, you get that easy confidence every time you ease awa