Heat Shrink Tubing 2:1 3:1 4:1 — Electrical Wire Sleeving, Multiple Sizes & Colors

Measure the outer diameter of the wire or connector you need to cover, then select a tube whose expanded (pre-shrink) inner diameter is slightly larger. After shrinking, the tubing will grip the surface tightly. For example, a 4mm tube at 2:1 ratio will shrink down to approximately 2mm (≈5/64"). When in doubt, size up one step — it is easier to shrink a slightly oversized tube than to force an undersized one over a connector.

The ratio describes how much the tubing shrinks in diameter when heat is applied. A 2:1 tube shrinks to half its original diameter — ideal for straight wire runs. A 3:1 tube shrinks to one-third, making it better for connectors and irregular shapes. A 4:1 tube shrinks to one-quarter, providing the tightest grip and typically used for large connectors, battery terminals, or when you need to cover a wide range of diameters with a single piece.

Polyolefin heat shrink tubing typically begins to activate at around 90 °C (194 °F) and fully shrinks at approximately 120 °C (248 °F). A heat gun set to low or medium is the recommended tool for even, controlled shrinkage. A lighter can work for small-diameter sizes in the field, but keep the flame moving to avoid scorching.

Standard polyolefin heat shrink tubing is generally resistant to moisture, UV exposure, and mild chemicals, making it suitable for many outdoor, automotive, and marine wiring applications. For fully waterproof or submersion-rated sealing, adhesive-lined (dual-wall) tubing is generally recommended. Contact us to confirm suitability for your specific environment before ordering.

The tubing is available in expanded inner diameters from 1.5mm (≈1/16") up to 85mm (≈3.35"), covering wire gauges from very fine signal wires (typically 26–28 AWG range) up to large battery cables (typically 2/0 AWG and above). Always select based on the outer diameter of the insulated wire, not the conductor gauge alone, as insulation thickness varies by wire type.

This tubing is made from polyolefin, a material widely used in electrical insulation applications and generally considered RoHS-compliant. It is typically flame-retardant in standard grades. If your project requires a specific certification (UL, CSA, MIL-SPEC, or similar), please contact us to confirm before ordering, as certification requirements vary by application and region.

Yes. Each piece is sold as 1 meter (≈39.4") and can be cut to any length with scissors or a utility knife before or after shrinking. Cut ends remain clean and do not fray, making it straightforward to prepare multiple pieces from a single meter for a wiring harness or repair job.