Composite insulators, also known as synthetic insulators, are made up of insulating elements consisting of a glass fiber resin core rod (or tube) and a jacket and hood made of organic materials. They are characterized by their small size, light weight, high tensile strength, and excellent antipollution 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, pole 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 the advantages of high mechanical strength, light weight, and small size tolerances, as well as the ability to avoid damage caused by shattering.