This standard outlines the specifications for bare, round copper-clad steel wire with 21% conductivity, used as the central conductor in tracer wire, also referred to as locating wire. Torsional Test: Measures wire's resistance to twisting Reverse Torsion Test: Assesses wire's strength under reverse twisting 21% Conductivity Extra High Strength (21EHS): Wire's high strength and conductivity Annealed 21% Conductivity Extra High Strength (21EHS-A): Wire's high strength and conductivity after heat treatment Color Black Material Copper-clad steel Item Form Solid Round Brand Name ASTM INTERNATIONAL Item Shape Cylinder Finish Type Unfinished Grade Rating Commercial/Industrial Recommended Uses For Product Tracer Wire