249-103-666 Clamp Kit Positive Negative New Style. Rugged PVC molded insulation surrounding the solid brass jaws and body. The 1000 amp booster clamps are ideal for heavy-duty battery chargers, jump starters. Our professional grade clamps have a PVC over molding applied to the outer surfaces to protect unexpected arcing with metal contact. The molded grips act as insulators and are rated up to 90°C (194°F).