When it comes to polyolefin heat shrink tubing, 3 to 1 heat shrink is the most useful for protecting irregular shapes in terminations or wire connections. Its properties, including its ability to shrink to one third its original size, make it a great choice for most applications.
This family of polymer plastics, which can be natural or synthetic, have a huge range of properties because of the way they are made up with large molecules that themselves are made up of smaller, repeating units. It's the length and flexibility of these "chains" that give a polymer its properties. Rubber, shellac, amber, silk, and wool are all polymers, yet all very different.
The material can perform continuously between temperatures of -55°C to +135°C (-67°F to +275°F), and the shrinking temperature is 100°C (212°F). It is generally not UV resistant.
A: Considered non-toxic, this class of plastic has both medical uses and food storage applications. Usually, the only elements in a polyolefin are hydrogen and carbon, although they sometimes include other elements in their matrix structure in order to give the final product properties like UV or flame resistance.
Since they are based on carbon, they are considered 100% organic.
A: Like 2:1, polyolefin 3:1 heat shrink tubing is intended for general use and will be adequate for most purposes. If you're not shrink-wrapping diesel fuel or chemical lines or running cable through extremely hot environments, then it will more than likely do the job. The wall final size of the tubing is actually thicker when shrunk than 2:1 heat shrink, so provides a better protection and tighter connection, especially for oddly shaped or bulky connectors.