This is a special part to restore the ideal roll center geometry 

The lower arm angle on a lower ride height vehicle tends to be far from ideal and the roll center point moves to a far low position. The deviation of the roll center from the center of the gravity results in a deteriorated cornering force due to the increased body roll.   Furthermore, the reduced suspension stroke leads to a diminished performance at the limit.

The J’s Racing roll center adjuster rectifies the situation by restoring the ideal roll center position (minimizing the deviation of the roll center and the center of the gravity) and produces the ideals suspension geometry

PRICE: 230€