3:1 Heat Shrink Tubing – Adhesive Glue Lined, Dual Wall, Waterproof Wire Sleeve

Measure the outer diameter (OD) of the cable, connector, or terminal you need to cover. Select a size whose expanded inner diameter is slightly larger than your cable OD — this allows you to slide the tubing on before heating. After shrinking at a 3:1 ratio, the tubing will grip tightly. For example, a 6.4mm (≈1/4") tube is typically suitable for cables in the 2–4mm OD range. When in doubt, size up rather than down to ensure easy installation.

A 3:1 shrink ratio means the tubing will shrink to approximately one-third of its original expanded diameter when heat is applied. For example, a 9.5mm tube will shrink down to roughly 3.2mm. This makes 3:1 tubing more versatile than standard 2:1 tubing — it can fit over larger connectors and still conform tightly to smaller cables in the same run.

Yes. The inner adhesive layer melts and flows during shrinking to create a moisture-resistant seal around the cable or connector. This makes it suitable for outdoor, marine, and automotive applications where exposure to water, humidity, or condensation is a concern. For fully submerged applications, contact us to confirm suitability for your specific use case.

This tubing generally begins to shrink at around 70°C (158°F) and fully activates the adhesive at approximately 120–150°C (248–302°F). A heat gun is the recommended tool — move it slowly and evenly along the tubing to avoid scorching. Avoid open flames such as lighters or torches, which can cause uneven shrinking or damage the outer jacket.

Yes. The dual-wall polyolefin construction is generally resistant to UV exposure, oils, and fuels, making it well-suited for automotive wiring harness repair, marine electrical connections, and outdoor junction protection. For prolonged UV exposure, black is typically the most resistant color option. Always verify the specific operating environment requirements with your application before installation.

Single-wall heat shrink provides basic insulation and strain relief but does not seal against moisture. Dual-wall (adhesive-lined) tubing — like this product — has an inner layer of hot-melt adhesive that bonds to the cable surface when heated, creating a waterproof, strain-relieved seal. This is the preferred choice for any application where moisture ingress, vibration, or mechanical stress is a concern.

Allow at least 5–10mm of overlap on each side of the area you want to cover. Heat shrink tubing also shortens slightly in length — typically 5–10% — when heated, so cut a piece slightly longer than your target coverage area to account for longitudinal shrinkage. For critical applications, test on a short piece first.