Review on High-Quality Oatey 39012 1.5 in. NPT ABS in-Line Vent in Black - Ultimate Plumbing Solution! by Michael Cox

This product performed exactly as intended, ie preventing duct gases from being released into the air. It attaches to the top of the drain pipe, which usually runs above the siphon, although it can be anywhere in your plumbing. It is typically installed where a plumber cannot get a vent pipe up and through the roof. This product is made of ABS material but I attached it to a PVC pipe and it works great. When the water flows, the disc inside opens to allow the water to flow properly, and then closes when the water shuts off. The old valve is usually easy to remove. You needed a wrench or channel locks to make it work. The new valve can be tightened by hand, simply stick Teflon tape on the threads. If you have any of these problems you need this valve: 1. Sewage smell around the drain.2. Slow drain 3. Drain flies. They will leak out through the valve if it leaks. The price is acceptable. All in all a good price and one of my best buys that fixed all three of the previously mentioned issues.