Heat shrinkable sleeves consist of specialized thermoplastic or cross-linked polyolefin materials. When exposed to heat (typically 90 °C–200 °C depending on the material), the sleeve contracts up to a predefined ratio (often 2:1, 3:1, or even 4:1), conforming tightly to the underlying substrate. Some variants include an inner adhesive (meltable) lining that flows during the shrinking process to form an impermeable seal, preventing moisture ingress and corrosion.
