MerCathode Gen III control unit 42600A09 is for all outboard and stern drive s. This is the replacement black control unit with the blue decal. Combat galvanic corrosion with this solid state controller for the MerCathode system. MerCathode self-adjusts to changes in the chemical content and temperature of the water and amount of exposed metal surfaces it needs to help protect. Easy to reconnect to existing wiring for the underwater elements of the system.Product Details Manufacturer part number: 42600A09 Replacement control unit with blue decal for Gen III MerCathode systems Combat galvanic corrosion with this solid state controller for the MerCathode system MerCathode self-adjusts to changes in the chemical content and temperature of the water and amount of exposed metal surfaces it needs to help protect Replaces Mercury 42600A3 Replaces Quicksilver 42600A3
