Oatey Air Admittance Valve with ABS Schedule 40 adapter is designed to serve as a reliable secondary vent for your plumbing system, capable of venting up to 160 DFU Branch or 24 DFU Stack. This valve features a one-way design that allows air to enter the plumbing drainage system whe negative pressure develops, eliminating the need for tying into a stack vent. Utilizing advanced technology, the valve opens precisely at -0.01 psi and seals securely at 0 psi or above, ensuring optimal performance. It fits vent pipes up to three inches in size, making it versatile for various installations. The valve includes a protective sleeve that simplifies installation and keeps debris away, while a screening on the air inlets protects the seal for long-lasting durability. Model Number: