These billet Mass Air Flow (MAF) bungs for 2011-2016 LML 6.6L Duramax engines are CNC machined from 6061-T6 aluminum in DeKalb, IL USA and ready to be welded to your custom aluminum air intake pipe. The bottom of the sensor block has been radius cut specifically for use with either 4" or 5" intake piping. Sensor mounting pad machined with arrow indicating proper direction of airflow to help you locate the sensor on your custom fabricated part in the correct facing. Compatible with GM Part Numbers: 23259883, 10393949