The QL Active Corrosion Protection System helps prevent galvanic corrosion from attacking the metal parts of your sterndrive or outboard. This system complements the sterndrive/outboard sacrificial anodes and is not intended to replace those. The QL Active Corrosion Protection System is recommended for fiberglass boats that are used in saltwater with varying degrees of corrosiveness, or where extra protection against corrosion is needed. The system is designed to protect the mass of one sterndrive or outboard. An additional kit is required for installation on a twin engine boat.