Bimetallic lugs are built employing two major materials: a high-conductivity aluminum barrel and a high-conductivity copper palm. The aluminum barrel, with a conductivity of approximately 60% IACS (International Annealed Copper Standard), is for safely receiving and terminating the aluminum conductor, and the copper palm, with a conductivity of up to 97% IACS, is joined to copper busb... https://www.pioneerpowers.com/bimetallic-lugs-and-connectors.php