Road Power's Extra Heavy-Duty Booster Cables feature Polar-Glo Clamps and T-Prene jacket insulation.. The Polar-Glo Clamp is ergonomically-designed so that it can be easily handled by everyone and it attaches itself firmly to both top and side post batteries. The clamps' triple-polarity identification includes color-coding indent stamping and glow-in-the-dark labels. In addition all energized clamp surfaces are shielded to avoid short circuits and all conductive clamp surfaces are recessed to prevent accidental contact and remains flexible even under the severest temperatures and is oil chemical and water resistant. Extra Heavy-Duty Booster Cables are made using 4 gauge wire and performs best with most vehicles including cars trucks or SUVs. This line of booster cables is UL Listed