The Zimmermann Brake Kit - Rear - 138862 is a comprehensive kit of products designed to service and maintain the rear brakes of a car. It includes a set of brake pads, brake rotors, brake calipers, and brake hardware. The brake pads are responsible for creating friction against the brake rotors to slow down or stop the vehicle. The brake rotors are the metal discs that the brake pads clamp onto. The brake calipers house the brake pads and use hydraulic pressure to squeeze them against the rotors. The brake hardware includes various small components such as clips, pins, and springs that help to secure and operate the brake system. This kit is designed to provide all the necessary components for a complete rear brake overhaul, ensuring optimal performance and safety for the vehicle.