Cable Sleeves are used to enclose a single wire or a group of wires. Cable sleeves are used to arrange a set of wires going through a panel or to an equipment like a motor. Cable sleeves are made of different materials from braided metals to rubber and even kevlar.
Sleeves serve to protect the wires and their insulation from sharp edges. They can protect wires from UV radiation, moisture, oil and temperature. 
In automobiles, special heat resistant sleeves are used to protect the wires from hot surfaces.
Teflon sleeves have great cut resistance. Nylon sleeves have great abrasion resistance.
Sleeves are available in two broad categories depending on the method of installation.
The first is the slit sleeve which is cut and the wires are inserted into the sleeve. The second is the wrap-around, side entry type of sleeve.
Heat Shrinkable Sleeves
Some sleeves are heat shrinkable. Heat shrinkable sleeves are made of a polymer which contracts when heat is applied. A stream of hot air from a blower is passed on the sleeve. This results in the sleeves shrinking and wrapping the wires.