Heat Shrink Tubing 2:1 Ratio – Electrical Wire Sleeving φ3.5mm to φ10mm

Select a size whose expanded inner diameter is slightly larger than the object you want to cover. With a 2:1 shrink ratio, the tubing will shrink to approximately half its listed diameter when heat is applied. For example, φ6mm (≈0.24") tubing will shrink to roughly 3mm (≈0.12"). Measure your wire or connector at its widest point and choose the next size up for easy installation.

A 2:1 ratio means the tubing shrinks to approximately half its original inner diameter when heated. So φ10mm (≈3/8") tubing will shrink down to roughly 5mm (≈3/16"), creating a snug, secure fit. This ratio is the most common for general electrical insulation and wire bundling tasks.

This tubing is typically activated at around 70–120°C (158–248°F). A heat gun is the recommended tool as it provides even, controlled heat distribution. For small diameters, a lighter can work in a pinch, but a heat gun gives the most consistent results and reduces the risk of scorching the tubing or the wire underneath.

Standard polyolefin heat shrink tubing generally offers good resistance to moisture and mild UV exposure, making it suitable for light outdoor and under-hood automotive use. For prolonged marine or harsh outdoor environments, adhesive-lined (dual-wall) tubing is generally recommended for a stronger environmental seal. Contact us if you need guidance for a specific application.

Polyolefin heat shrink tubing of this type is generally rated for up to 600V in standard low-voltage electrical applications. It is commonly used in automotive (12V–48V), electronics (signal and power wiring), and light industrial wiring. For high-voltage or code-critical installations, please contact us to confirm the exact rating before use.

The size range of φ3.5mm to φ10mm covers a wide spectrum of wire gauges. As a general guide: φ3.5–4mm typically suits AWG 20–24 signal wires; φ5–6mm suits AWG 14–18 general wiring; φ7–10mm suits AWG 6–12 heavier power cables. Always measure the actual wire bundle diameter — including any connectors or solder joints — before selecting a size.

Yes — this is one of the most popular uses. With 7 color options (Black, White, Red, Green, Yellow, Blue, and Transparent), you can follow standard wiring color conventions or create your own color-coding system for circuit boards, control panels, and automotive wiring harnesses. The transparent option lets you inspect the connection underneath without removing the sleeve.