Progressive 444 Series Shocks for Harley Review http://www.revzilla.com/motorcycle/pr... After more than a decade of ruling the streets with the road proven 440 Series shocks, Progressive unveiled another breakthrough design in the 444. Dubbed Frequency Sensing Technology (FST) for its unique ability to dynamically adjust damping as you ride. The result is superior performance no matter the road conditions. A top mount threaded preload adjuster allows for fine tuning with a simple twist of the cap.

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