This special radiator cap features a sacrificial magnesium anode that protects aluminum and Other soft material engine components from electrolysis. Electrolytic metal ersosion (eme) is slowly destroying your engine components and attachs timing chain covers, radiators, heater cores, intake manifolds, freeze plugs, head gaskets and evein cylinder heads causing premature failures. By allowing eme to attack the sacrificial anode, this cap protects your engine while driving or in storage. Concourse correct appaearance, 14 pound rating. Stop electrolysis!