Waterproof sleeve, also known as wall penetration sleeve or penetration pipe. Flexible waterproof sleeves are generally suitable for structures that experience vibration during pipe penetration through walls or have strict waterproofing requirements. After local processing of the sleeve, a primer coat (including linseed oil or cold primer) is applied to the outer wall. Waterproof sleeves are divided into rigid and flexible types. The main difference between them lies in their primary applications; flexible waterproof sleeves are mainly used in places with high requirements like civil air defense walls and ponds, while rigid waterproof sleeves are typically used in underground pipelines where pipe架ing is necessary.