Outboards and outdrives are particularly prone to galvanic corrosion because of the use of different exposed metals. For this reason, many are fitted with multiple anodes. It is important to know where every anode is located as, consult your owner's manual then and check and replace any that are more than half depleted. A fin is intended to warn of depletion by a change in steering. ElectroGuard anodes are precision die cast which means they fit right every time.
