Select a tube whose expanded (pre-shrink) inner diameter is at least 20% larger than the widest point of the object you're covering. With a 2:1 shrink ratio, the recovered diameter will be approximately half the expanded size. For this 210mm tube, the recovered diameter is typically around 105mm (≈4.1"). Measure your cable or bundle at its widest point — including any connectors — before selecting your size.

This tubing uses a 2:1 shrink ratio, meaning it shrinks to approximately half its original expanded diameter when heat is applied. So a 210mm expanded tube will typically recover to around 105mm. This is the most common ratio for general electrical insulation, wire bundling, and cable sleeve applications.

Polyolefin 2:1 heat shrink tubing generally begins to shrink at around 70°C (158°F) and fully recovers at approximately 120°C (248°F). A heat gun is the recommended tool for even, controlled shrinkage. Move the heat gun steadily along the tubing to avoid scorching. Avoid open flames where possible, as they can cause uneven shrinkage or damage.

Standard polyolefin heat shrink tubing generally provides basic moisture resistance and UV tolerance suitable for short-term or incidental outdoor exposure. The black color offers better UV resistance than clear tubing. For long-term outdoor, marine, or fully waterproof applications, we recommend confirming suitability with us — adhesive-lined (3:1) tubing may be a better fit for those scenarios.

Polyolefin heat shrink tubing of this type is generally self-extinguishing and rated for standard electrical insulation applications. It is typically RoHS compliant and meets common flame-retardancy standards. If your project requires specific certifications (UL, CSA, MIL-SPEC), please contact us before ordering to confirm this product meets your requirements.

Use sharp scissors or a utility knife on a flat surface for the cleanest cut. Cut the tubing slightly longer than the area you need to cover — typically add 5–10mm (about 1/4") on each end — to account for any end pull-back during shrinking. Score lightly first if the tubing is thick, then cut through in one firm motion.

Wall thickness after full recovery is typically in the range of 0.6mm–1.5mm for standard 2:1 polyolefin tubing, depending on the specific diameter. The exact recovered wall thickness for this 210mm size may vary — contact us to confirm if precise wall thickness is critical for your application.