They are usually made of composite materials. However porcelain insulators are also available. They are also lighter and have greatly reduced chances of catastrophic failure. Hollow Insulator also have excellent seismic resistance.
The hollow tube in these insulators can be made of FRP. Fibre reinforced Plastic has excellent resistance to bending and can be used in cantilever-type applications.
These insulators can be manufactured in a number of shapes such as conical, cylindrical and straight inner or outer appearance.