Mild Steel Zinc Plated Hex Bolt Bung Plug for Oxygen Sensor Bung M18x1 2 Sets O2 OXYGEN SENSOR M18 X 1.5 BUNG & PLUG WIDEBAND WELD ON IN NUT Stainless Steel O2 Oxygen Sensor Weld On Bung M18 x 1.5 + Steel plug mm O2 Sensor Bung End Plug Pipe Stainless Steel M18x1.5 Oxygen Hex Vibrant Standard O2 Sensor Weld Bungs T304 SS M18 x 1.5 thread. All Vibrant Performance exhaust bungs are made from the highest quality stainless and mild steel to ensure the utmost in quality for all professional aftermarket and O. E. M Exhaust projects.