Waterproof sleeve is generally referred to as wall penetration sleeve. The wall penetration sleeve is also known as wall penetration pipe, waterproof sleeve, pre-buried wall pipe, and waterproof sleeves are divided into rigid waterproof sleeves and flexible waterproof sleeves. In the electrical field, those used for electrical conductivity are called AC wall penetration sleeves. They can be categorized by material into dry-type capacitor AC wall penetration sleeves and porcelain insulated AC wall penetration sleeves, abbreviated as silicone rubber sleeves and porcelain sleeves, respectively.