Used on VULCAN 400 (1999). The Idling Adjustment Knob located underneath the OEM air cleaner is difficult to use. In order to make the Idling Adjustment Knob easier to use, I installed this product which is a smaller type than OEM. As a result, the Idling Adjustment Knob can now be moved to the same height as the Cleaner and can be adjusted without disturbing the riding position. The quality of the product is fine, but note that you will need to prepare a 2.5M Hexagon Nut.