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Insultherm® Spark Plug Boots

Spark Plug and Ignition Wire Protection


High Temperature Protection

For decades, Techflex®’s Insultherm® braided fiberglass sleeving has been the first choice among automotive professionals and enthusiasts alike for many of their thermal protection applications. These innovative sleeves offer the same high temperature protection in an easy slip on sleeve that will extend the life of expensive spark plug wires by protecting them where they need it most... at the boot. Just slip these 3/4” diameter double thickness (triple thick at the sewn end) sleeves over any spark plug cable and boot (even right angle boots) to protect them from engine temperatures up to 1,200°F. Once installed, the sleeves require no clearance from hot surfaces, and can even rest directly on hot exhaust headers without affecting performance. Insultherm Spark Plug Boot Sleeves are completely non-conductive, resist all engine chemicals, will not support combustion, and provide an easy, economical solution to the challenge of wire protection in the cramped, high temperature environment of any high performance engine compartment.


  • Resin Coated Fiberglass
  • Will Not Burn or Support Combustion
  • Easy, No Tool Installation
  • Operating Temps: -94°F to 1,202°F (-70°C to 650°C)
  • Extremely Abrasion and Cut Resistant
  • Resists Common Chemicals & Solvents
  • Available In 4 Colors
  • Melt Temp: 2,048°F/1,120°C

About The Insultherm® Family of Products

Insultherm® products are extremely high temperature resistant material commonly used as thermal protection for wires, cables and hoses that are subjected to continuous and extreme high temperature environments, such as engine manifolds and exhaust systems.

Insultherm®:This traditional sleeving is tough and durable, maintaining its tight structure under extreme vibration, abrasion, mechanical stress, and temperature variations.

Insultherm® Heavy Duty: This is a braided fiberglass sleeving made in a heavy wall construction with a high temp cord braided into the sleeving. Insultherm® HD is saturated with high temperature acrylic resins which adds rigidity and reduces fray when cut.

Insultherm® Tru-Fit: Tru-Fit is often used as primary insulation on low voltage applications such as leads in toasters, coffee makers, ranges, and other appliances. This product is available in a wider range of colors than standard Insultherm®.

Insultherm® Ultra Flex®: Ultra Flex® expands slightly, allowing it to slide easily over wires and follow curves and contours without binding. It is compatible with most bonding & saturation systems.

Insultherm® Ultra Flex® Pro: Ultra Flex® Pro cuts easily with scissors, and special heat treated construction minimizes fraying and dusting during assembly. The Increased wall thickness adds value to insulation.

Insultherm® Spark Plug Boots: These innovative sleeves offers high temperature protection in an easy slip on sleeve that will extend the life of expensive spark plug wires by protecting them where they need it most... at the boot. Just slip these 3/4” diameter double thickness (triple thick at the sewn end) sleeves over any spark plug cable and boot (even right angle boots) to protect them from engine temperatures up to 1,200°F.

Insultherm® Header Wrap: Insultherm® Header Wrap is an extremely high temperature resistant wrap commonly used to contain and manage hot gases in automotive and high performance headers and exhausts.

Insultherm® Header Wrap SI: This exhaust wrap is made from texturized amorphous silica filament yarn woven into a strong and flexible form. Because the yarn is texturized into a bulky form it provides excellent insulating values. Header Wrap SI is not made from leached fiberglass, resulting in a much more wear resistant finished product


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