HellermannTyton 321-20680 Adhesive-Lined Heat Shrink Tubing, 68 mm, 3.5:1, Black, 1 m

With a 3.5:1 shrink ratio and a 68 mm expanded inner diameter, this adhesive-lined heat shrink tubing delivers robust sealing and insulation for demanding cable joints. The dual-wall design combines a cross-linked polyolefin outer layer with an inner adhesive that melts during shrinking, creating a waterproof barrier against moisture and contaminants.

Overview

HellermannTyton 321-20680 is a 1-meter length of black heat shrink tubing engineered for insulation, sealing, strain relief, and cable protection. It shrinks to approximately 19.43 mm inner diameter when heated to a minimum of 110 °C, conforming tightly to irregular shapes. The tubing operates reliably from -55 °C to +110 °C, making it suitable for harsh environments.

What stands out

• Adhesive lining provides a waterproof seal after shrinking
• Self-extinguishing flame retardant material
• Good UV and chemical resistance for outdoor and industrial use
• Dielectric strength of at least 15 kV/mm for electrical insulation

Technical details

• Expanded inner diameter: 68 mm
• Recovered inner diameter: 19.43 mm
• Shrink ratio: 3.5:1
• Length: 1 m
• Material: Cross-linked polyolefin
• Minimum shrink temperature: 110 °C
• Operating temperature range: -55 °C to +110 °C
• Dielectric strength: ≥15 kV/mm
• Flame retardant: Self-extinguishing
• UV resistance: Good
• Chemical resistance: Good
• Waterproof: Yes (after shrinking)
• RoHS compliant

Our verdict

A reliable choice for heavy-duty cable sealing and insulation, offering excellent environmental protection and electrical performance in a single, easy-to-use product.