vent systems 4" inch duct connector flange with square spigot wall plate – dryer vent adapter and mounting plate – ideal for seamless hvac ductwork connections, exhaust fans, and airflow management 4 inch / 100 mm galvanized is up for auction in Tools & Home Improvement. The current bid is $0.05, 100% below the $23.99 MSRP, in Good Condition. This auction has ended — similar items appear in live auctions regularly.