Black Heat Shrink Tubing 2:1 — 0.6mm to 12mm, Multiple Lengths

Measure the outer diameter of the wire or bundle you need to cover, then select a tubing size whose pre-shrink inner diameter is at least 10–20% larger than that measurement. With a 2:1 shrink ratio, the tubing will shrink to approximately half its original diameter. For example, 4.0mm tubing will shrink down to roughly 2.0mm — so it works well on wires up to about 2.0mm OD.

Quick inch reference: 1.0mm ≈ 0.039", 3.0mm ≈ 0.118", 6.0mm ≈ 0.236", 10mm ≈ 0.394", 12mm ≈ 0.472".

A 2:1 shrink ratio means the tubing will shrink to approximately half its original inner diameter when heat is applied. For example, a 6.0mm tube will shrink down to roughly 3.0mm, conforming tightly around the wire or component. The wall thickness increases proportionally, improving the mechanical protection of the covered area.

This tubing generally activates at around 70–90°C (158–194°F) and fully shrinks at approximately 120°C (248°F). A heat gun set to a low or medium setting is the recommended tool — move it steadily along the tubing to avoid scorching. A lighter can work in a pinch but may cause uneven shrinkage or discoloration.

This tubing is made from polyolefin, which typically offers good resistance to UV exposure, moisture, and mild chemicals, making it generally suitable for outdoor wiring applications such as landscape lighting, garden irrigation controllers, and exterior junction boxes. For prolonged submersion or extreme chemical environments, an adhesive-lined (3:1) variant may provide a better seal.

As a general guide based on typical wire OD measurements:

• 0.6–1.0mm — very fine wires, typically 28–32 AWG
• 1.5–3.0mm — small signal wires, typically 22–26 AWG
• 3.5–6.0mm — standard hookup wire, typically 16–22 AWG
• 7.0–10mm — heavier gauge wire, typically 10–16 AWG
• 11–12mm — thick cables or small wire bundles

Always verify by measuring your wire's outer diameter directly, as insulation thickness varies by manufacturer.

Yes. Polyolefin heat shrink tubing is commonly used in automotive wiring repairs, harness protection, and connector insulation. It is generally resistant to engine bay temperatures, oils, and vibration. For connections exposed to fuel or brake fluid, verify chemical compatibility before use. The 2:1 ratio is the standard choice for most automotive applications.

Use sharp scissors or a utility knife for a clean, straight cut. Cut the tubing slightly longer than the area you need to cover — typically 5–10mm (about 1/4") extra on each end — to account for any minor longitudinal shrinkage that may occur during heating and to ensure full coverage of the joint or splice.