4 AWG Heavy wall lugs are extra heavy duty copper cable lugs with tin plating to resist corrosion. The increased wall thickness makes for a solid crimp and each lug is color coded with the crimp die and crimp position(s). With more copper mass in each lug compared to other 4 AWG heavy duty lugs you can expect maximum life and conductivity. The tinned copper will not turn black or green like non-plated copper lugs. These extreme 4 AWG lugs can be crimped or soldered and ideal for battery terminal connections. These lugs are sized to properly fit flexible stranded copper cable and wire gauge sizes.