This optional secondary spring is primarily used as an addition to the DUV P9XP clutch kit for mud use with the extra large 29.5" and larger tires. It can also be used with 28" tires if they are the extreme mud competition tires and primary use is mud, or with other 28" if use is for primarily sand. For most other typical trail applications with Trail/Mud tires and occasional mud, the regular clutch kit is most efficient and this spring is not used.

Instructions are included in the "set up guide" of the regular clutch kit for these applications when adding this spring.