This is an Alcoa 225393 Stabilizer Extension Kit for 22.5 inch wheels with on center hole positions. This kit includes two H-2225 grommet stabilizers and two HE-392 valve extensions. H-2225 grommet stabilizers work with a 2.00 inch diameter hand hole and HE-393 valve extensions have a 1 inch long collar and a 6 inch effective length. Proper air pressure is the most important factor in lengthening tire life. On dual wheel assemblies, the inner dual is many times overlooked or improperly serviced. The Alcoa Extension and Stabilizer Kit allows access to the inner dual tire valve and properly positions and supports the extension for servicing. The stabilizer reduces the road vibration on the extension and practically eliminates valve stem breakage caused by vibration. Alcoa Wheels is an American company that produces and processes aluminum products worldwide. They are pioneers and creators of products as common today as aluminum foil and are present in several industries such as aviation and heavy transport. Alcoa Wheels designed the first forged aluminum truck wheel in 1948 and Alcoa represents more than 120 years of experience in the production of aluminum along with more than 60 years in forged aluminum truck wheels and accessories. Their automated production lines guarantee quality standards that meet the most demanding demands of heavy transport. Rest assured that Alcoa products will keep you running down the road.