Kuryakyn 509 18mm Oxygen Sensor Bung Plug Since 1989, Kuryakyn has been the world&#39;s leading provider of innovative and stylish bolt-on chrome parts and accessories for a wide variety of motorcycles. From Harleys to Hondas, Kuryakyn has something for everyone and has now expanded the product line to include sport bikes and many others.12 or 18 mm sensor bung plugs for the Kuryakyn Crusher Touring Head Pipes.Sold as a pair.Note: Kuryakyn part number: 5