The Zimmermann Brake Kit - Rear - 138629 is a comprehensive kit of products designed for use on the rear brakes of a car. It includes a variety of components that are essential for maintaining and improving the performance of the rear brakes. The kit contains four objects, each serving a specific function in the brake system. These objects include brake rotors, brake pads, brake wear sensors, and brake pad retaining pins. The brake rotors are circular discs that are attached to the wheel hub and rotate along with the wheel. The brake pads are the friction materials that press against the rotors to slow down or stop the car. The brake wear sensors are electronic devices that alert the driver when the brake pads need to be replaced. And finally, the brake pad retaining pins are metal clips that hold the brake pads in place. This kit is a convenient and cost-effective solution for those looking to replace or upgrade the rear brakes on their car.