Be sure that you are buying the right chuck for automatic Nitrogen inflation systems. Proven to work with over 100,000 chucks sold. Pack of (8) standard Nitrogen Service Tire Chucks. If you are filling 2-6 tires with an automatic inflation system, you have to use Nitrogen Service Tire Chucks or you will have Error Code issues with your inflation system. The Nitrogen Service Chuck is a "Closed" chuck while the common off the shelf tire chuck is an "Open" chuck. Buy our proven closed chucks for Nitrogen tire filling!