Color-Keyed® metric lugs are manufactured from electrolytic copper tube. The dimensions of the tube are designed to obtain the most efficient electrical conductivity and mechanical strength, resisting vibration and pullout. Color-Keyed® metric lugs are annealed to guarantee optimum ductility, which is a necessity for compression connectors having to withstand severe deformation arising when compressed or bending of the tongue that may happen during installation. Connectors have to perform adequately with vibration loads and annealing is necessary to avoid material failure between the barrel and the tongue. The presence of an inspection hole facilitates full insertion of the conductor and the barrel length is designed to allow easy and accurate positioning of the dies during the crimping operation. Lugs are electrolytically tin-plated to eliminate oxidation of the copper material.