Heat Shrink Tubing 2:1 Ratio — φ25mm to φ210mm, Multiple Colors & Lengths

Select a diameter that is at least 20–30% larger than the object you need to cover before shrinking. For example, if your cable bundle measures 20mm across, choose the φ25mm size. After applying heat, the tubing shrinks to approximately half its original diameter (2:1 ratio), creating a snug, secure fit. When in doubt, size up — tubing that is slightly oversized before shrinking is easier to work with than tubing that barely fits.

This tubing uses a 2:1 shrink ratio, meaning it shrinks to approximately half its original inner diameter when heat is applied. For example, φ50mm tubing will shrink down to roughly φ25mm. This ratio is the most common for general-purpose electrical insulation and cable bundling applications.

Generally, polyolefin heat shrink tubing begins to shrink at around 90°C (194°F) and fully recovers at approximately 120°C (248°F). A heat gun is the recommended tool — move it evenly along the tubing to avoid hot spots. Avoid open flames, which can cause uneven shrinkage or scorching, particularly on larger diameters like φ100mm and above.

Polyolefin heat shrink tubing is generally moisture-resistant and suitable for many outdoor applications such as marine cable protection and outdoor electrical junction insulation. However, for prolonged UV exposure or harsh chemical environments, an adhesive-lined or UV-stabilized variant is typically recommended. Contact us to confirm suitability for your specific outdoor use case.

Yes, polyolefin heat shrink tubing is generally flame-retardant and meets common electrical safety standards. It is widely used in automotive wiring harnesses, electronics manufacturing, and industrial cable management where fire resistance is a requirement. If you need certification documentation for a specific standard (e.g., UL, RoHS), please contact us to confirm.

Each diameter is designed to fit a range of cable sizes before shrinking. As a general guide: φ25mm fits cable bundles up to ~20mm OD; φ50mm fits bundles up to ~40mm OD; φ100mm fits bundles up to ~80mm OD; φ150mm fits bundles up to ~120mm OD. Always measure your cable or connector outer diameter before selecting a size. For connectors or irregular shapes, measure the widest point.

Color selection is typically based on wiring convention or personal preference. Black is the most common for general-purpose insulation. Red is often used for positive leads, while other colors help with color-coding and identification in complex wiring harnesses. Transparent tubing allows you to see the underlying wire or label after installation — a practical choice for labeled cable runs or heat shrink wire connector applications where visual inspection is needed.