Black Heat Shrink Tubing 2:1 Ratio – Waterproof Wire Sleeving, φ0.6mm–φ210mm

Select a pre-shrink diameter that is generally 20–30% larger than the object you need to cover. For example, for a 4mm wire bundle, choose φ5mm or φ6mm tubing. After shrinking, the tubing reduces to approximately half its original diameter (2:1 ratio), so the recovered size will be roughly half the listed pre-shrink diameter. When in doubt, size up — you can always shrink tighter, but you cannot stretch the tubing back out.

A 2:1 shrink ratio means the tubing will shrink to approximately half its original inner diameter when heat is applied. For example, φ10mm (≈3/8") tubing recovers to roughly φ5mm (≈3/16"). This ratio is suitable for most standard wire insulation, bundling, and connector boot applications. If you need a tighter fit over irregular shapes, a 3:1 or 4:1 ratio tube may be more appropriate.

Once fully shrunk, this tubing provides a snug, moisture-resistant seal suitable for most indoor and outdoor applications including automotive, marine, and garden lighting wiring. It is a single-wall (non-adhesive) tube, so it does not create a fully hermetic seal. For submersion-rated or high-pressure water environments, a dual-wall adhesive-lined heat shrink tube is generally recommended.

This tubing typically begins to shrink at around 70–90°C (158–194°F) and fully recovers at approximately 120°C (248°F). A heat gun set to low or medium is the recommended tool for even, controlled shrinkage. A lighter or match can work for small diameters (φ0.6mm–φ6mm) in a pinch, but may cause uneven shrinkage or surface scorching on larger sizes.

Yes. This black polyolefin heat shrink tubing is generally manufactured to meet UL224 flame-retardant standards, meaning it will self-extinguish when the heat source is removed. It is not intended for use in direct flame, arc-flash, or high-voltage environments beyond its rated voltage. Contact us to confirm the specific voltage rating for your application before ordering.

Yes — automotive wiring repair is one of the most common use cases for this heat shrink wire sleeving. The polyolefin material is resistant to fuels, oils, and common automotive fluids in most cases. It works well for protecting wire splices, wrapping connector boots, and reinforcing harness sections in engine bays, door panels, and undercarriage wiring runs.

To convert millimeters to inches, divide by 25.4. Here are some common conversions for this product: φ1mm ≈ 0.04", φ6mm ≈ 0.24" (≈15/64"), φ10mm ≈ 0.39" (≈3/8"), φ25mm ≈ 0.98" (≈1"), φ50mm ≈ 1.97" (≈2"), φ100mm ≈ 3.94" (≈4"), φ210mm ≈ 8.27" (≈8 1/4"). Select the variant that matches your pre-shrink requirement.

For single wire splices or connector boots, 1M–3M is generally sufficient for most repair jobs. For wiring harness projects, cable management runs, or workshop use, 5M–10M is a practical starting point. Larger rolls (15M–50M) are typically chosen by electricians, automotive shops, or makers who work with heat shrink tubing regularly and want to minimize per-meter cost.