3:1 Without Glue Heat Shrink Tubing 1.5mm-50mm Dia Insulation Flame Retardant

A 3:1 ratio means the tubing shrinks to one-third of its expanded (pre-shrink) diameter when heat is applied. For example, a 6mm expanded tube recovers to approximately 2mm. When selecting a size, choose a tube whose expanded diameter is at least 10–20% larger than the object you are covering, so it slides on easily before shrinking down to a firm, snug fit.

No. This is a dry-wall (without glue) heat shrink tubing. It provides mechanical insulation and strain relief but does not create a waterproof seal on its own. If you need a moisture-proof or fully sealed connection, consider pairing it with a separate adhesive-lined (dual-wall) tube or applying sealant at the ends after shrinking.

Yes. The polyolefin material is formulated to be self-extinguishing — it will not continue to burn once the external heat source is removed. This makes it suitable for automotive wiring harnesses, control panel wiring, and other enclosed environments where fire propagation is a concern. It is not rated for continuous direct flame exposure.

Measure the outer diameter of the wire, connector, or bundle you want to cover. Select a heat shrink tube whose expanded diameter is roughly 1.2× to 1.5× that measurement so it slides over easily. After shrinking, the recovered diameter will be approximately one-third of the expanded size. For example, for a 4mm cable, a 6mm expanded tube (recovering to ~2mm) provides a firm grip. For a 10mm bundle, a 15mm tube is a good starting point.

Yes, with the understanding that this is a dry-wall tube without an adhesive seal. Once shrunk, the polyolefin material resists UV exposure, mild chemicals, and mechanical abrasion, making it suitable for outdoor cable runs and marine wiring. For fully waterproof connections in submerged or high-moisture environments, an adhesive-lined tube is recommended instead.

A standard heat gun set to 120°C (248°F) or higher is the most reliable tool. You can also use a soldering station with a hot-air nozzle. Move the heat source evenly along the length of the tube, working from the center outward to prevent air pockets from forming. Avoid holding the heat gun in one spot, as this can cause uneven shrinkage or scorching. A lighter or match can work for short pieces in a pinch, but a heat gun gives the most consistent result.

Color selection is typically driven by wiring standards or personal preference. Common conventions include: Black for ground or negative conductors, Red for positive or live wires, Yellow for caution or signal lines, Blue for neutral in some regional standards, Green for earth/ground in European wiring, and White for neutral in North American systems. Using color-coded heat shrink makes future troubleshooting and inspection significantly faster.