Rubber Material---Swimming pool rubber plugs are made of rubber material for maximum expandability to ensure a tight seal. Used as pipe plugs, to plug skimmers, returns and cleaner lines, to prevent water from entering the pipes during winter. Easy to Use---You just simply screw the plugs into all return and drain inlets after blowing out lines, with proper dimension, convenient to handle and use, won't take you much effort Multi Function---Expansion plugs have other uses too, such as pressure testing pool lines or other methods of leak detection, or stopping water flow from the pool when equipment repairs are made. Good Effect---Protect your swimming pool from the harsh winter with antifreeze plugs. A simple solution can prevent serious damage to your pool. Good Workmanship---These rubber plugs are designed to plug your swimming pool pipes after they have been drained to avoid water from entering the pipes and causing freeze influence. Exquisite workmanship, beautiful appearance design, small and portable size, providing you great using experience.