None. CouplerTec employs a technology known as capacitive coupling; the couplers are fixed to the vehicles painted surface. Any product that uses anodes or runs a wire straight to a screw or bare metal is using cathodic/impressed current technology that was designed for boats or underground pipes etc., NOT motor vehicles.
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Another year gone and our 35 year old Landcruiser HJ60 is still shiny and No rust! at Abenteuer & Allrad show in Bad Kissingen, the biggest offroad exhibition in Europe.