Heat shrink tube use to cover electrical joints. This is non electrical material and perfect replacement of electrical tape. Heat tube are much more efficient to cover electrical wiring joints and looks more professional. Heat tubes size can be varry +/- 1 mm depending upon stock.
Upon heating heat tube shinks and protect inner wire and joints. Use Lighter, hair dryer, heat gun to heat heat tube.
Heat Tube Specification -
Size - 3mm
Length - 1 meter
Colour  - Black