This bung adapter kit is made by Rinehart Racing specifically for their 2012-Newer Softail and Dyna full exhaust systems.
Adapter bung kit reduces the 18mm 02 ports down to 12mm.
Kit is needed if you are using a Rinehart 2012-Newer full exhaust system on a Softail or Dyna and you are not going to use an auto tune system such as the Thundermax Auto Tune or the Dynojet Auto Tune modules.
If you do plan on using a wide band aftermarket tuning device then you do not need this adapter kit.
(2) 18mm to 12mm O2 Sensor plug adapters
The Air Resources Board (ARB) does not permit the use of aftermarket emission-related parts that alter the air/fuel ratio of an emission-controlled vehicle. Due to these legal restrictions this part cannot be shipped to California.