18mm Heat Shrink Tubing 2:1 — Electrical Insulation Sleeving, 7 Colors

Measure the total cable run you need to cover and add 10–15% extra for overlap and trimming. For example, a 3-meter wire harness typically needs at least a 3 Meter roll, while larger wiring projects generally benefit from the 5 Meter or 10 Meter options to avoid mid-run splices. If you're stocking a workshop, the 15 Meter or 20 Meter (≈65.6 ft) rolls offer the best value per foot.

A 2:1 shrink ratio means the tubing shrinks to approximately half its original inner diameter when heat is applied. This 18mm tubing will typically shrink down to around 9mm (≈3/8"), creating a snug, insulating sleeve over your wire or cable bundle. The wall thickness increases proportionally, improving mechanical protection at the joint.

18mm inner diameter (≈11/16" before shrinking) generally fits cable bundles, conduit ends, and wire harnesses in the range of roughly 9mm–16mm outer diameter. Always measure your cable OD before ordering to confirm fit. If your cable OD is close to 18mm, the tubing may not shrink tightly enough — consider a smaller size.

This tubing is generally suitable for protected outdoor use where it is shielded from prolonged UV exposure and standing water. For fully exposed marine or direct-burial applications, a dual-wall adhesive-lined heat shrink is typically recommended for added moisture resistance and waterproofing. Contact us if you need guidance on the right product for your environment.

Standard polyolefin heat shrink tubing like this typically activates at around 90°C (194°F) and fully shrinks at approximately 120°C (248°F). A heat gun set to medium heat is the recommended tool for even, controlled shrinkage. An open flame (lighter or torch) can be used carefully but may cause uneven shrinkage or surface scorching if held too close.

This heat shrink tubing is made from polyolefin material, which is generally flame-retardant and suitable for standard electrical insulation, wire bundling, and strain relief applications. It is commonly used in automotive, marine, and low-voltage electrical projects. Contact us to confirm compliance documentation (RoHS, UL, etc.) for your specific project requirements.

Yes. Before shrinking, the tubing cuts cleanly with standard scissors or a utility knife. For the cleanest edge, cut perpendicular to the tube axis. After shrinking, the material becomes firmer — wire cutters or a sharp blade work best for trimming cured sections. Buying a longer roll (5 Meter or 10 Meter) gives you flexibility to cut custom lengths for multiple jobs.