A bi-metallic lug is a type of special electrical connector used to connect two dissimilar conductors—aluminium cable and copper bus bars—quickly and safely. Bi-metallic lugs are built with two different metals—the aluminium barrel and the copper palm. The aluminium barrel is constructed to connect the aluminium cable, while the copper palm connects to the copper bus bar or terminal. ... https://www.pioneerpowers.com/bimetallic-lugs-and-connectors.php