The differential adjustment key for a Citroen 11CV is a specialized tool used for tuning and maintaining the differential in this classic vehicle. It is essential to keep the drivetrain's performance optimal and minimize wear. Precision-engineered, it makes adjustments more efficient and helps prevent unwanted vibrations or noises during driving. This tool is critical for vintage car enthusiasts and mechanics to keep the Citroen in top condition, contributing to the overall driving experience and vehicle reliability.