Progressive 412 Shocks For Harley Dyna The 412 Series shocks are simply the best value shock on the market. The have a simple, durable design which means they will be an improvement to your motorcycle's suspension performance for as long as you are riding. They feature a doublewall steel body construction with nitrogen charged, multi-staged velocity sensitive valving resulting in smooth, consistent damping. A cam style preload adjuster lets you dial in your ride whether you're a light or heavy rider. Features: 5-position cam style preload adjuster High Pressure Gas Charged for consistent damping performance Standard or Heavy-Duty progressive rate springs Available with chrome or black full cover Backed by a one-year limited warranty