Waterproof sleeve, also known as wall-passing sleeve or pipe-through-wall sleeve. Flexible waterproof sleeves are generally suitable for structures subjected to vibration or have stringent waterproof requirements during pipe wall penetration. After local processing of the sleeve, a coat of primer (including camphor or cold primer oil) 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 like civil air defense walls and pools with high requirements, while rigid waterproof sleeves are generally used for pipelines in basements and similar structures where pipe installation is required.