Eliminate the need for a branch vent with the Oatey Sure-Vent Air Admittance Valve. This air admittance valve (AAV) provides the ideal venting solution for island sinks, remote bathroom groups, and remodel jobs by eliminating the need to be connected directly into the stack vent. This AAV keeps the sewer and atmospheric pressures equalized, allowing water to drain freely. Its one-way valve is designed to allow air to enter the plumbing drainage system when negative pressures develop without the use of a vent extended to open air and to prevent sewer gases from escaping into the building. The Oatey Sure-Vent AAV is sensitive to pressure changes to consistently open and close as needed by the plumbing system, closing by gravity and sealing the vent terminal at zero differential pressure (no flow conditions) and under positive internal pressures. This 1.5" x 2" PVC air admittance valve is approved to handle up to 3" vent pipe and has a 20 DFU (Drainage Fixture Unit) capacity. It complies to ASSE (American Society of Safety Engineers) Standard 1050 and 1051 for use a secondary vent. Since 1916, Oatey has provided reliable, high-quality products for the residential and commercial plumbing industries, with a commitment to delivering quality, building trust and improving lives. Today, Oatey operates a comprehensive manufacturing and distribution network to supply thousands of products for professional builders, contractors, engineers and do-it-yourself consumers around the world.