J Speed 86 / BRZ Sublock

Car Make: Toyota / Subaru
Model: 86 / BRZ

Even if the rear member is a rubber mount and the arm is made into a pillow, if the mounting part moves, the rear grip will become unstable. By rigidly mounting the rear member to the body, it also functions as a sub-frame and achieves a precise and stable rear grip.

For more details please go through the below link...
Reinforcement/reinforcement parts