Mercury - Square Aluminum Anode Corrosion Protection Aluminum Alloy 875208. Overview. If you spend enough time around outboards, you learn which parts quietly save you money - and anodes are high on that list. The Quicksilver 875208 Aluminum Anode is one of those small but essential guardians that protect your engine from the steady, invisible wear of galvanic corrosion. It's a simple piece of metal, but the reassurance it gives you out on the water is real. Knowing your outboard's housing and k