The Oatey Sure-Vent Ultra provides 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. The Sure-Vent Ultra is a one-way air admittance 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. The Oatey Sure-Vent Ultra offers UNMATCHED PERFORMANCE by providing market leading airflow, country specific push-on EPDM gaskets for OPTIMIZED INSTALLATIONS, superior Sweet Spot Technology opening and closing under the smallest pressures, providing a lifetime of reliability.