3:1 Blue Adhesive Heat Shrink Tubing — Waterproof Glue Lined Sleeving

Select a pre-shrink diameter that is larger than the object you need to cover. With a 3:1 shrink ratio, a φ9.5mm (≈3/8") tube will shrink down to approximately φ3.2mm (≈1/8"). As a general rule, choose a pre-shrink diameter that is 20–30% larger than the cable or connector outer diameter. For example, a 6mm cable typically works well with a φ9.5mm tube. When in doubt, size up — you can always apply more heat to achieve a tighter fit.

A 3:1 shrink ratio means the tubing will shrink to approximately one-third of its original inner diameter when heat is applied. This is generally more versatile than standard 2:1 tubing, making it suitable for irregular shapes, stepped connector profiles, and applications where a tighter recovered fit is needed over a wider range of substrate sizes.

Yes. The inner adhesive lining melts and flows when heat is applied, creating a moisture-resistant seal around the substrate. This makes it suitable for outdoor wiring, marine environments, and applications where moisture ingress is a concern. For full submersion applications, please confirm suitability with your specific requirements before use.

Typically, a heat gun set to around 90–120°C (194–248°F) is sufficient to activate shrinkage and melt the adhesive lining. Move the heat gun evenly along the tubing to avoid hot spots. Avoid using an open flame, as uneven heat can damage the tubing or the underlying wire insulation. A dedicated heat gun is recommended over a lighter or torch.

Yes. The adhesive-lined construction provides resistance to moisture, dust, and mild chemical exposure, making it commonly used in automotive wiring harness repairs, marine electrical connections, and outdoor junction box protection. For high-vibration or extreme-temperature environments, confirm the operating temperature range matches your application requirements before installation.

This tubing is generally compatible with standard copper and aluminum wire insulation, as well as most connector housings used in automotive, marine, and general electrical applications. It is not designed for use with bare conductors without insulation. Check the pre-shrink inner diameter against your connector's outer diameter before ordering to ensure a proper fit.

For single repairs or splices, 1m (≈3.3 ft) is typically sufficient. For wiring harness projects or runs along a vehicle chassis, 5m (≈16.4 ft) or 10m (≈32.8 ft) rolls offer better value per meter. The 15m (≈49.2 ft) option is well-suited for workshop stock or larger installations. We recommend adding 10–15% extra to your estimated length to account for trimming and positioning.