This item is a Multi-bend chrome elbow. It is also available in different diameters. This one in particular is design to fit on top of Kenworth W900 Models with 40 inch tool box. 

It has 7 inches in diameter and it is reduced to 5 inches on the bottom end to fit properly to the system underneath your truck. 

This particular stack is usually sold as part of a bundle/kit; along with the 7 inch spool and top stack of your choice.

If you are looking to get a whole set of stacks, please contact us and we will gladly assist you in putting together the pieces you need.

If you only need to replace this single piece on your existing stack set, then you are in the right spot!