Confused by some of the terminologies around heat shrink? To help industry professionals and home users make better purchasing choices, we have prepared a glossary of some important heat shrink terms.

The first half of the glossary breaks down different products sold on the website. The second half includes more general terms that you will come across when using heat shrink. 

Part One: Heat Shrink Products


A direct alternative to Tyco/Raychem SRFR, FB-SRFR is a silicone rubber heat shrink tubing product that stays flexible at extreme temperatures and has good physical and electrical resistant properties. FB-SRFR is widely used in medical applications where a sterile environment is key.

Heat gun

The recommended tool for applying heat shrinkable material. Heat shrink guns can be used with special nozzles like a reflector nozzle to make application easier and more uniform.

Heat shrink breakout boots

Heat shrinkable products that provide protection for cables when wires need to be split into two, three or four separate cables. 

Heat shrink connectors and splices

Heat shrinkable products that provides a resistant seal around exposed wires for connections or splicing.

Heat shrink end caps

Heat shrinkable material formed with a solid cap on one side. These products are typically used to seal insulated wires and cables against moisture.

Heat shrink tape

Heat shrink tape is a special adhesive lined tape which will shrink when heated. The tape can be wrapped around components and unusual shapes to give better protection.


Another heat shrink tubing product with good resistance to high temperatures and fluids. The semi-rigid, translucent tubing has dozens of approvals and can be used in military and aerospace applications.


Thin-walled and semi-rigid, HLAT is a special kind of heat shrink tubing from Hilltop Products. It is a good electrical insulator and has a low shrink temperature, so is easy to use. This product is ideal for wrapping custom batteries.


HLST is a flexible heat shrink product that can be used in extreme low temperatures. HLST is not flame retardant, but it does meet the automotive flame propagation standard MVSS 302 for use in vehicles.


A flame-retardant heat shrink tubing product that offers good performance at a low cost. This PVC product represents a cost-effective material for a variety of applications including cable installation and insulation.


Made from PTFE, HPTF is translucent heat shrink tubing product with very high-temperature resistance and a good range of other properties. It has been approved for use in military and medical sectors alongside many others.


Manufactured by Hilltop Products, HSP1 is a tough and flexible general-purpose heat shrink tube with good resistance to common fluids and solvents. It also has a high dielectric strength, so it is a good insulator.


A high-grade heat shrink tubing solution from Hilltop Products. HSP2 has a strong blend of physical, chemical and electrical properties. The material specification is approved for use in military and aerospace applications such as wire harness jackets and insulation.


Another premium heat shrink tubing product from Hilltop Products, HSP3 has a heat shrink ratio of 3:1. It also has good physical, chemical and insulating properties and can be used for certain military applications.


Flat, flame retardant heat shrink tubing that can be printed with a thermal transfer printer for excellent print quality. HSP3F has a 3:1 shrink ratio and is predominantly used to label cables and components in electric panels, wire harnesses and other applications.


A low-smoke, zero halogen heat shrink tubing. This flexible heat shrink tubing meets the flammability requirements set out in the UL-224 standard and can be used for insulation and other purposes in a wide variety of settings.


A zero-halogen heat shrink tubing product that is ideal for cable identification. PET-ZH tube walls are thin and lightweight and absorb very little water. It is widely used in chemical, mechanical and agricultural applications.


RT-375 is a thin wall heat shrink tubing product that is tough and flame resistant. The transparent fluoropolymer is also resistant to chemicals and can be used for certain military applications.


Used in a variety of commercial and military applications, Versafit provides high flame retardance, good flexibility and a low shrink temperature for faster installation.


Manufactured using a cross-linked fluoroelastomer, Viton-HT has good fluid and chemical resistant properties. It can be used when a cable is likely to contact different fuels, lubricants, acids and solvents.


A flat, zero-halogen heat shrink tubing that can be used in thermal transfer printing and labelling. Because the material is zero halogen, it means it is flame retardant and meets the material specification for sectors including aerospace, railway and other sensitive environments.

Part Two: Heat Shrink Terminology


This is the process of creating new covalent bonds between a polymer’s atoms to create plastic memory. Once a thermoplastic has been cross-linked and stretched to an expanded shape, it will shrink back to its original dimensions when heat is applied – making heat shrink possible.

Expanded inside diameter (or expanded ID)

The diameter of the inside of a heat shrink tube before it is heated and shrunk. This refers to the inside diameter of a tube as it is supplied. It is also equal to the total diameter of the tube, less the wall thickness. 

Full recovery temperature

The temperature at which heat shrink tubing will shrink to its recovered diameter. Tubing with a lower recovery temperature will be quicker to install. Tubing with a high full recovery temperature may require specialist heating equipment.

Inside diameter

The diameter of the inside of a heat shrink tube. If purchasing online, this will usually refer to the inside diameter of a tube as it is supplied. It is also equal to the total diameter of the tube, less the wall thickness.

Longitudinal shrinkage

As well as shrinking in diameter, heat shrink tubing will also contract slightly lengthways. If heat shrink length is critical to your application, then you should check the longitudinal shrinkage in the product specification.

Low smoke zero halogen (LSZH)

Also known as low smoke-free of halogen, LSZH is a material classification typically used in cable jacketing. LSZH heat shrink is made from a thermoplastic that emits limited smoke and no halogen when it is exposed to heat, reducing the amount of toxic and corrosive gas emitted during combustion.


Polyolefin is a type of thermoplastic that includes polyethylene (PE) and polypropylene (PP). These are two of the most common materials used in heat shrink products. Non-polyolefin heat shrink products are made from materials including PTFE, PVC and Viton. They have a number of qualities including fluid resistance, high-temperature resistance and abrasion resistance.

Operating temperature range (or continuous operating temperature)

Indicates what range of temperatures heat shrink tubing can be exposed to safely without failing. Only heat shrink tubing products that are made to withstand higher temperatures should be used for highly sensitive applications.


Polyolefin is a type of thermoplastic that includes polyethylene (PE) and polypropylene (PP). These are two of the most commonly used heat shrink materials. Polyolefin products are flexible, fast-shrinking and can be used across a range of operating temperatures. Polyolefin heat shrink tubing is widely used in military, aerospace and railway applications.


One of the most commonly used heat shrink materials. PVC is available in a wide range of colours, they are a little cheaper and can withstand high but not extreme operating temperatures.

Recovered inside diameter (or recovered ID or minimum recovered ID)

The diameter of the inside of a heat shrink tube after it has been heated and fully shrunk. Sometimes it is referred to as minimum recovered ID, because tubing may not shrink fully when heated. 

Shrink ratio

Indicates how much a heat shrink tube’s inside diameter will contract from its original (expanded) size.


Global safety standard for insulating heat shrink tubing. The standard relates to the flammability of the tubing and means heat shrink tubing has a level of flame retardance.

Wall thickness

The diameter of the heat shrink tube walls. Tube walls will become thicker once a product has been heated to full recovery.