The Genuine VW / Audi Control Arm Kit - 178123 is a comprehensive kit of products designed for use in a car. It includes four different components, each with a specific function in maintaining and improving the performance of the vehicle. The first component is a control arm, which is a vital part of the suspension system that connects the wheel hub to the chassis of the car. This helps to support the weight of the vehicle and allows for smooth steering and handling. The second component is a ball joint, which is a pivot point that connects the control arm to the steering knuckle. This allows for the control arm to move up and down while still maintaining a stable connection to the wheel. The third component is a bushing, which is a rubber or polyurethane piece that helps to absorb shock and reduce vibration in the suspension system. The final component is a bolt, which is used to secure the control arm and other components in place. Together, these four components make up the Genuine VW / Audi Control Arm Kit - 178123, providing a complete solution for maintaining and improving the performance of a car's suspension system.