This part is the replacement short outboard TCA joint for the Elise S1 with Steel Uprights and Elise S2 & VX220 with straight inserts in the uprights.
The original TCA joint might wear out, run dry or the thread might break. It is of great importance to check these regularly. If the joint runs dry and starts rusting, the toe link might snap.
The application of this TCA joint is outlined in service bulletin 2003/11 issue 6.