Don’t know if you can get it down under but this is the tubing I used:

XHF 2 Inch (50mm) 3:1 Waterproof Heat Shrink Tubing Marine Grade Wire Cable Adhesive Lined Tube Insulation Seal Against Moisture Corrosion and Air Leakage, 4 Ft Red

And here is the heat gun:

Hangar 9 Heat Gun HAN100 Hand Tools Misc