Usage: The antifreeze plug in the swimming pool is used as a pipe plug to prevent pipeline freezing and blockage in winter. It can also be used as an expansion plug in pressure testing or leak detection, or to prevent water from flowing out of the pool during equipment maintenance. Material: The antifreeze plug is made of stainless steel bolts and expandable rubber, which is cold resistant, anti slip, non shrinkage, durable and firm. Packaging: 2 stainless steel bolts, black rubber anti freeze expansion plugs, 2-inch size. It can meet your daily use and replacement needs, and the freezing plug can protect your swimming pool from the harsh winter. You can use our antifreeze rubber plugs in outdoor and indoor swimming pools by simply screwing the plugs into all pipe, return, and drain ports