Standard copper Primary Wire and Cable is widely used in the trailer and automotive industries for original equipment and replacement wiring. The General Purpose Thermo-Plastic (GPT) Insulation is highly resistant to acids, gasoline, oil, grease and most industrial solvents. Meets SAE J1128 specifications. For use with 60 volts or less; under 176°F (80°C). The 4 wires are then insulated and protected by a thick jacket.