Waterproof sleeve generally refers to wall penetration sleeve. Wall penetration sleeve is also known as wall penetration pipe, waterproof sleeve, pre-buried wall pipe. Waterproof sleeves are divided into rigid waterproof sleeve and flexible waterproof sleeve. In electrical applications for electrical conductivity, it is called AC wall penetration sleeve. Depending on the material, it can be classified into dry-type capacitor AC wall penetration sleeve and porcelain-insulated AC wall penetration sleeve, respectively abbreviated as silicone rubber sleeve and porcelain sleeve.