Jones Stephens has built its reputation over the years as a leader in the plumbing industry, providing the market with thousands of products to complete any project. The Sewer Stopper/Backflow Preventer is used inside a drain line to help guard against backups. It creates a seal in the pipe to reduce sewer gases. The sewer stopper secures into place with set screws and features a compression fit. Available in a variety of sizes to suit your needs. Material: Brass.