Check the listing for details. O2 Oxygen Sensor STEPPED Nut Recess Bung M18 X 1.5 Threads - Stainless - 10-Pack. Condition: New. Listed at 24.98 USD. STEPPED / RECESSED STYLE - O2 sensor weld bungs made of 304 Stainless Steel - 10-Pack (10 pieces) special with Free Expedited USPS Priority Shipping! Ships out of California today and you'll receive it in 2-3 days anywhere in the USA. The thread pitch is 18mm x 1.5 which is typical O2 sensor thread pitch for 99% of O2 (oxygen sensor) sensors in the market place. These are high quality FAB-PROS weld bungs with the STEP to drop right into the hole you drilled in your round tube for precise welding. Very shallow step for minimal to no protrusion into the pipe. Very nice design! Get them while they last. We will ship them and provide TRACKING the moment we get your order so you don't have to wait and wonder if they will arrive on time for your project. Thank you!