OATEY 1.5" ? 2" 20 DFU SURE-VENT AAV With 1-1/2? X 2? PVC Schedule 40 Adapter Product Description Oatey? Sure-Vent? 20 DFU Capacity Air Admittance Valve's one-way valve allows air to enter the plumbing drainage system when negative pressures develop in the piping system. The purpose of an Air Admittance Valve is to provide a method of allowing air to enter the plumbing drainage system without the use of a vent extended to open air and to prevent sewer gases from escaping into a building. An Air Admittance Valve is a one way valve designed to allow air to enter the plumbing drainage system when negative pressures develop in the piping system. The device shall close by gravity and seal the vent terminal at zero differential pressure (no flow conditions) and under positive internal pressures. From the Manufacturer Oatey products can be found in residential and commercial applications and have achieved excellent brand name recognition with consumers. All products are backed with the highest quality technical and customer support programs in the industry Features Complies to ASSE Standard 1050 and 1051 For use as a secondary vent One size approved to handle up to 3" vent pipe Opens/closes as needed by building's plumbing system Rated 20 DFU?s for venting DWV 2? and smaller USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.