Penske's hydraulic preload adjuster adds the ability to change spring preload for a variety of reasons. If you want the change the ride quality of your ride, or maybe you have added a passenger, or you want to hit the canyon roads. No need to break out the tool and bust your knuckles with the old spanner collar. Now just a quick turn of the little knob can change the spring preload and make you ride much better. 
 
8mm of adjustable preload
Initial preload can be changed with split ring on shock body
Remote mounted adjustment knob connected with steel braided line.
**If updating an existing Penske shock specify hose lenght needed.