The patented WP Tension Improvement system was developedin cooperation with world champions in offroad racing andis ideal for use in combination with a preload adjuster. The WP TI system comes as a separate item butmust only be used in combination with an originalWP Preload Adjuster made for the same type ofWP TRAX shock absorber. The WP TI system is available for all WP TRAX 5018Shocks with a MY 2016 PDS system and older.