Progressive Suspension 444 Series Standard Shocks 12.5in. - Chrome 444-4207C Features the all new Frequency Sensing Technology (FST) which allows the shocks to sense the frequency of a bump and automatically adjust damping for superior ride quality Deflective disc valving Adjust spring pre-load by hand, no special tool needed Includes a progressive rate spring and is high-pressure gas charged for consistent performance Standard or heavy duty spring rate with a black or chrome finish