* Thread Spring Preload or adjustable spring screw. By threading the cylindrical shock absorbers, user can turn the preload to fine tune the spring & tighten a provided bolt to fix the ring in its position * Adjustable length. It helps increase the length of the shock absorber. The two types can be upgraded to 10 mm or adjustable lengths +/- 5 mm. Article: YSS Rear twin shock external reservoir Gas Eco Line