3:1 Ratio 4mm Adhesive Heat Shrink Tubing — Glue Lined Waterproof Sleeving

Measure the total length of wire or connector you need to cover, then add at least 10–15% extra for overlap and positioning. Available lengths range from 1 metre (≈3.3 ft) up to 20 metres (≈65.6 ft). For single repairs, 1m or 3m is typically sufficient; for wiring harness projects, 10m–20m rolls are generally more economical.

A 3:1 shrink ratio means the tubing shrinks to one-third of its original diameter when heat is applied. For this 4mm (unshrunk) tubing, the recovered inner diameter is typically around 1.3–1.5mm, allowing it to grip tightly around small wires, terminals, and connectors that a standard 2:1 tube would not seal as effectively.

Yes. This tubing features a dual-wall construction with an inner adhesive (glue-lined) layer. When heated, the adhesive melts and flows around the substrate, creating a moisture-resistant seal. It is generally suitable for outdoor wiring, marine environments, and automotive applications where moisture ingress is a concern.

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 is recommended for even, controlled shrinkage. Avoid open flames, which can scorch or unevenly shrink the tubing.

The 4mm unshrunk inner diameter generally accommodates wire bundles or connectors up to approximately 3.5mm in diameter. After shrinking, the recovered diameter is typically around 1.3–1.5mm. For best results, the unshrunk tubing should slide over your wire or connector with a small amount of clearance — a snug but not forced fit.

Yes. The glue-lined adhesive layer provides a watertight seal that is generally suitable for automotive wiring harnesses, boat wiring, and outdoor electrical connections. The tubing is typically rated to withstand vibration, UV exposure, and temperature fluctuations common in these environments. Confirm specific ratings with your application requirements before use in safety-critical circuits.

Color selection is typically used for wire identification and organization. Common conventions include black for ground, red for positive, blue for signal, yellow for caution circuits, green for earth/ground (in some standards), white for neutral, and clear when you want the underlying wire color to remain visible. Choose based on your wiring standard or personal preference.