Frequency Sensing Technology (FST) allows the shocks to sense the frequency of a bump and automatically adjust damping for superior ride qualityAdjust spring pre-load by hand, no special tool neededProgressive Rate Main springs specifically designed for touring944 FST Ultra Touring shocks are available in three configurations: Standard (Up to 250 lb), Heavy-Duty (250 to 350 lb) and Super Heavy Duty (350+ lb)Made in the USASits 2” lower on most models.Before purchasing or attempting to install shocks that are different than the OEM length, confirm that your wheel travel can be altered without causing clearance issues, such as swingarm/axle to exhaust contact as well as chain/belt guard or tire contact.