Available in Black, Blue and Red Closely woven fiberglass impregnated with high voltage, leak resistant silicone which adds up to 8,000 volts of extra insulation Extend spark plug wire life by adding insulation against exhaust header heat For best results, we recommend that the sleeve cover the full length of wire from spark plug boot to distributor boot and sealed with Shrink Sleeve No. 72030 or No. 72031 Nos. 72000, 72002, 72004 fits 7 & 8mm wire.