The copper inslulated terminal cages are made from high-grade, strain-**** and corrosion proof copper alloys. They won’t experience any electrolytic corrosion or rusting, even when moisture is present. The metal surfaces are protected with a lead-free, galvanic nickel or tin plating. The good electrical conductivity permits only a low temperature rise. https://www.blfspchina.com/termi...ter-screw-terminals.html