Composite insulators, also known as synthetic insulators, are made up of insulating components consisting of a glass fiber resin core rod (or core tube) and a jacket and hood made of organic materials. They are characterized by their small size, light weight, high tensile strength, and excellent anti-fouling and flashover performance. However, their resistance to aging is not as good as that of porcelain and glass insulators. Composite insulators include rod-type suspended insulators, insulating crossarms, pillar insulators, and hollow insulators (i.e., composite sleeves). Composite sleeves can replace porcelain sleeves used in various electrical equipment such as transformers, surge arresters, circuit breakers, capacitor sleeves, and cable terminations. Compared to porcelain sleeves, they offer higher mechanical strength, lighter weight, and smaller size tolerances, as well as the advantage of avoiding damage caused by shattering.