Techflex Insultherm Tru-Fit Fiberglass Sleeving, 3/8” ID, Black
Quick Overview
- Techflex Insultherm Tru-Fit fiberglass sleeving, 3/8" ID
- Fits wire or bundle OD 0.375 to 0.399 in (9.5 to 10.1 mm)
- Braided fiberglass, acrylic treated: low fray, low dust
- Rated 464 degrees F (240 C); UL VW-1; very high abrasion resistance
- Sold by the foot; black
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$0.78
per Feet (USD)Techflex Insultherm Tru-Fit Fiberglass Sleeving, 3/8" ID, Black, Sold by the Foot
Braided fiberglass sleeving, heat treated and acrylic coated so it does not fray or shed: insulates single wires, sensor leads and small lines near heat. UL VW-1.
Techflex Insultherm Tru-Fit is braided fiberglass that has been heat treated and impregnated with an acrylic binder to reduce fraying and dust. Racetronix is a Techflex distributor. It slides over individual wires, thermocouple and sensor leads, soldered joints and small lines to add heat and abrasion protection without bulk. Unlike an expandable braid it hardly stretches: each size fits a narrow range, so match it to what you are covering. This is the 3/8" ID, inside diameter 0.375" to 0.399" (9.5 to 10.1 mm), sold by the foot.
Key features
- Fiberglass for heat: the maker's catalogue rates Tru-Fit to 464°F (240°C); its data sheet lists the fiberglass to 1,202°F (650°C). Use 464°F as the working limit.
- UL VW-1 flame rating.
- Very high abrasion resistance in the maker's test.
- Acrylic treated: low fraying and dust; flexible down to -94°F (-70°C); resists most organic solvents.
- Cuts with scissors.
In pictures
Which size do I need?
Measure the outside diameter of the wire or bundle, insulation included, and choose the size whose inside-diameter range includes it. The AWG sizes are named after the bare wire gauge they match, so an insulated wire usually needs a larger size than its gauge number: measure rather than going by gauge.
| Part | Size | Fits OD from | Fits OD to | Wall | Weight per foot |
|---|---|---|---|---|---|
| 299-FGLG.14BK | 14 AWG | 0.064" (1.6 mm) | 0.072" (1.8 mm) | 0.011" | 0.0028 lb |
| 299-FGLG.10BK | 10 AWG | 0.102" (2.6 mm) | 0.112" (2.8 mm) | 0.011" | 0.0035 lb |
| 299-FGLG.07BK | 7 AWG | 0.144" (3.7 mm) | 0.158" (4.0 mm) | 0.013" | 0.0048 lb |
| 299-FGLG.04BK | 4 AWG | 0.204" (5.2 mm) | 0.224" (5.7 mm) | 0.016" | 0.0063 lb |
| 299-FGLG.02BK | 2 AWG | 0.258" (6.6 mm) | 0.278" (7.1 mm) | 0.016" | 0.0102 lb |
| 299-FGLG.00BK | 0 AWG | 0.325" (8.3 mm) | 0.347" (8.8 mm) | 0.016" | 0.0178 lb |
| 299-FGL0.38BK | 3/8" | 0.375" (9.5 mm) | 0.399" (10.1 mm) | 0.016" | 0.0179 lb |
| 299-FGL0.44BK | 7/16" | 0.438" (11.1 mm) | 0.462" (11.7 mm) | 0.018" | 0.0204 lb |
| 299-FGL0.50BK | 1/2" | 0.500" (12.7 mm) | 0.524" (13.3 mm) | 0.018" | 0.0228 lb |
| 299-FGL0.63BK | 5/8" | 0.625" (15.9 mm) | 0.655" (16.6 mm) | 0.018" | 0.0256 lb |
| 299-FGL0.75BK | 3/4" | 0.750" (19.0 mm) | 0.786" (20.0 mm) | 0.018" | 0.0416 lb |
Sizes are sold by the foot. Pre-cut packs: LOOM-F-10-25 (10 AWG, 25 ft), LOOM-F-2-10 (2 AWG, 10 ft), LOOM-F-3-8-10 (3/8", 10 ft), LOOM-F-4-15 (4 AWG, 15 ft).
Equivalents: other brands' fiberglass sleeving
Shopping for another brand? These are coated fiberglass sleeves in similar sizes. They expand more and are rated differently, so they are near equivalents.
| Our part | Instead of (brand) | Their part number | Description | Match |
|---|---|---|---|---|
| 299-FGL0.38BK | Heatshield Products | 204011 / 204101 | Hot Rod Sleeve 3/8", 10 ft / 100 ft | Near equivalent |
| 299-FGL0.50BK | Heatshield Products | 204012 / 204102 | Hot Rod Sleeve 1/2", 10 ft / 100 ft | Near equivalent |
| 299-FGL0.75BK | Heatshield Products | 204014 / 204104 | Hot Rod Sleeve 3/4", 10 ft / 100 ft | Near equivalent |
| 299-FGLG.00BK | Heatshield Products | 203124 | Color Sleeve, black, 5/16"-7/16" x 25 ft | Near equivalent |
| 299-FGL0.38BK | Heatshield Products | 203124 | Color Sleeve, black, 5/16"-7/16" x 25 ft | Near equivalent |
| 299-FGL0.44BK | Heatshield Products | 203124 | Color Sleeve, black, 5/16"-7/16" x 25 ft | Near equivalent |
Other brands' names and part numbers are their owners' trademarks, listed only to help you compare. Check sizes against your application.
Specifications
| Construction | Braided fiberglass, heat treated, acrylic binder |
| Size | 3/8" ID |
| Fits outside diameter | 0.375" to 0.399" (9.5 to 10.1 mm) |
| Temperature | Catalogue: 464°F (240°C). Data sheet: fiberglass 1,202°F (650°C) maximum continuous, -94°F (-70°C) minimum |
| Flammability | UL VW-1; halogen free |
| Abrasion | Very high (maker's test) |
| Cutting | Scissors |
| Sold as | By the foot, black |
Fitting Tru-Fit sleeving
- Slide the sleeving over the wire before you crimp or solder the terminal.
- Wrap a turn of tape where you will cut, then cut through the tape with scissors to keep the end neat.
- Over a soldered joint, center the sleeving over the joint.
- Hold the ends with heat shrink or a tie.
Which heat protection do I need?
Heat reaches a hose or wire in three ways, and each needs a different kind of protection.
- Radiant heat. A header or turbo throws heat out in every direction, like a stove element, and it reaches anything in line of sight. Reflective foil stops it best: the aluminized face bounces it back before it gets in.
- Heat soak. Hot air and nearby hot parts warm a line slowly and steadily. Insulation stops it. Braided fiberglass traps thousands of tiny pockets of still air, the same way the insulation in a house wall does, and still air carries heat very poorly. Squash the fiberglass and the air goes, and most of the insulation with it.
- Flame, sparks and splash. A burst line, a backfire or weld spatter. This needs a covering that will not burn: a silicone jacket or a non-flammable fibre.
Foil-over-fiberglass products combine the first two: the foil reflects, the fiberglass insulates. Nothing should rest against a bare header; wrap the header, shield the line, or both.
| Situation | Use | Why it works |
|---|---|---|
| The exhaust itself: headers, down pipes, turbo crossovers | Header wrap | Keeps the heat inside the pipe, so far less of it radiates onto the hoses, wiring and bodywork around it. The best fix is usually at the source. |
| A hose or harness close to a header or turbo (strong radiant heat) | T6 ThermaShield split tube or ThermaShield Convoluted | The aluminized face reflects most of the radiant heat before it gets in, and the fiberglass behind it insulates against what does get through. |
| A firewall, floor pan, fuel cell or ECU box facing the exhaust | ThermaShield Flat or ThermaShield Wrap | The same foil over fiberglass, as a sheet that sticks on or wraps around odd shapes. |
| Lines in a hot engine bay: steady heat soak, little direct radiant heat | FireFlex fire sleeve | A thick layer of fiberglass holds still air, which insulates; the silicone jacket seals out oil, fuel and splash. Leave at least 1/8" of air gap so the fiberglass is never squashed. |
| Single wires, sensor and thermocouple leads near heat | Insultherm Tru-Fit fiberglass sleeving | A thin fiberglass braid that insulates without adding bulk. |
| Plug wire boots close to the headers | Insultherm spark plug boot sleeves | Double-thick fiberglass where the boot sits closest to the pipe. |
| Flame, sparks, weld spatter or molten splash | Dragon Sleeve, or FireFlex if the line also needs insulating | Dragon fibre will not burn and shrugs off sparks, but its thin wall holds little air, so it does not insulate much. FireFlex resists splash and insulates. |
All the lines compared:
| Product | What it is | Heat it handles | Continuous rating | How it fits | Best for |
|---|---|---|---|---|---|
| Techflex FireFlex fire sleeve | Thick fiberglass braid with a silicone jacket | Direct heat, open flame, oil and fuel splash | 500°F (260°C) | Slides on before the hose ends go on | Fuel, oil, brake and clutch lines near headers or turbos |
| Techflex T6 ThermaShield split tube | Aluminized fiberglass tube, split, closes with an adhesive strip | Reflects radiant heat | 491°F (255°C) material; reflects radiant heat from a 1,400°F source at 3/8" | Wraps around: no need to remove fittings | Assembled hoses and harnesses near exhaust |
| Techflex ThermaShield Convoluted | Seamless aluminized fiberglass, flexible convoluted tube | Reflects radiant heat | Not published | Slides on | Hoses and wires that bend in several directions |
| Techflex ThermaShield Flat (full adhesive) | Flat aluminized fiberglass with a full adhesive back | Reflects radiant heat | Not published | Sticks to any clean surface | Firewalls, floor pans, fuel cells, ECU boxes |
| Techflex ThermaShield Wrap (adhesive edge) | Flat aluminized fiberglass joined along one edge by adhesive | Reflects radiant heat | Not published | Wraps around odd shapes | Connectors, sensors, short runs |
| Techflex Insultherm Tru-Fit fiberglass sleeving | Acrylic-treated braided fiberglass | Direct heat, no flame or fluid seal | 464°F (240°C) | Slides on | Individual wires, thermocouple and sensor leads |
| Techflex Insultherm spark plug boot sleeves | Double-thick fiberglass sleeves, 7-1/2" long | Direct heat at the header | 1,200°F | Slips over the boot | Plug wire boots close to headers |
| Techflex header wraps: Insultherm, Header Wrap SI, Volcano Wrap | Woven tape wrapped around the pipe | Keeps heat inside the exhaust | Fiberglass 1,200°F; silica 2,000°F; basalt 1,300°F | Wrapped with 1/4" overlap, tied at the ends | Headers, down pipes, turbo crossovers |
| Techflex Dragon Sleeve | Thin double-wall braid of non-flammable Dragon fibre | Flame, sparks, weld spatter, molten splash; not an insulator | None published; the fibre decomposes at 842°F (450°C) | Slides on; the braid expands | Lines and wires exposed to sparks or open flame |
| Techflex Weld Wrap HD | Silicone-coated silica braid with hook-and-loop closure | Weld spatter, slag, sparks; heat | 500°F (260°C) continuous; 2,000°F (1,093°C) intermittent | Wraps on with hook-and-loop | Welding leads and hoses; lines that see sparks |
Frequently asked questions
Why two temperatures, 464°F and 1,202°F?
The fiberglass itself is listed to 1,202°F (650°C), but the catalogue rates the finished sleeving at 464°F (240°C), which covers its acrylic coating and whatever is inside. Plan on 464°F.
What does "10 AWG" mean here?
It is the bare wire gauge the sleeving matches: 10 AWG size fits 0.102" to 0.112". Most insulated wire is larger than its bare gauge, so measure the outside of the wire and use the chart above.
Tru-Fit or FireFlex?
Tru-Fit for single wires and small leads where bulk matters. FireFlex for hoses and larger lines that need a thick insulating layer and a silicone jacket against flame and fluids.
Ratings are the maker's published figures.
