The Zimmermann Brake Kit - Rear - 138731 is a comprehensive kit of products designed for the rear brakes of a car. It includes various components that are essential for maintaining and improving the performance of the rear brakes. The kit contains four different objects, each serving a specific purpose. These include brake pads, rotors, calipers, and brake hardware. The brake pads are responsible for creating friction against the rotors to slow down or stop the vehicle. The rotors are the discs that the brake pads clamp onto. The calipers are the devices that hold the brake pads and apply pressure to them. Lastly, the brake hardware consists of various small parts such as bolts, clips, and springs that are necessary for the proper functioning of the brakes. This kit is suitable for a wide range of car models and provides all the necessary components for a complete rear brake replacement or upgrade.