This is ARC R8.3(E) Adjustable Front Shock Base.
The adjustable front shock base is the latest option part designed for the ARC R8.3 and R8.3E. This allows the shock angle to be adjusted by adding or removing shims
Compared to traditional shock towers, racers can adjust the shock angle in much finer increments to better fine tune the handling of their car - with more shims below the shock absorber standing the shock up and making the suspension harder
The new shock base also features a 3mm carbon brace that bridges the left and right sides of the shock base. This brace can be added or removed to adjust the flex of the front bulkhead. With the plate installed, front side flex with be reduced resulting in an increase in initial corner speed.