Heat-shrink tubing
The unshrunk tubing is fitted on the wire before making the connection, then slid down to cover the joint after it is made. If the fit is tight, silicone lubricant can be applied without compromising the heat-shrink material. The tubing is then shrunk to wrap tightly around the joint by heating in an oven or with a hot air gun or other source of hot gas flow. Convenient but less consistent methods for shrinking the tube include a soldering iron held close to but not touching the tube, or the heat from a lighter. Uncontrolled