I replaced the stock Harley automatic chain tensioner with the Hayden unit on my 2012 Dyna Switchback. The stock unit only has one direction; tighter and tighter. The Hayden mounts on springs so it keeps constant tension on the primary chain. Install was easy and straight forward. I did have to file the metal portion of the unit a little because the nylon shoe was a little tight in spots on its mounting bracket. After filing, the shoe rides up and down smoothly in the mounting bracket. I also felt the price was a bit high for what you get too. But it is a big improvement over the faulty Harley stock unit. And I felt the Harley Screamin' Eagle unit wasn't a much better design. And its reviews said it was loud. The Hayden unit is quiet.