Do it 1-1/2 Inch MIP Mechanical ABS Vent Valve eliminates the need for expensive secondary vent stacks, making it a practical choice for various drainage applications. It is suitable for sinks, basins, tubs, showers, vanities, and washing machines, but should not be used for toilets. Featuring 1-1/2" male pipe threads, this vent valve is conveniently packed one per Do it card for easy handling. Each drainage system using a mechanical vent must include a main vent stack that vents to the atmosphere through the roof, specifically positioned to vent the water closet. For optimal performance, avoid installing the mechanical vent in a sealed wall cavity; it should be placed in a location that is readily accessible. Installation is limited to structures that do not exceed two stories in height and that do not have corrosive water. Model Number: 403636