Exit series X1 center track shocks are piggyback reservoir configurations. All come standard with HTC springs, and pre load adjustable. All aluminum parts are anodized for a durable long lasting finish. X1 series shocks stand for compression adjustable with a simple knob that has 24 clicks of tuning adjustment. Exit shock technology comes from 15+ years of off-road and snowmobile racing experience to give you the ultimate in ride quality, which is easily serviced for years of reliable use. All Exit shocks come with our ride quality guarantee. If for any reason your not satisfied with the way they are performing. Just call us within the first 30 days of use. We will re spring, and re valve until you are satisfied, no charge.