The Zimmermann Brake Kit - Rear - 138830 is a comprehensive set of products designed for use on a car's rear brakes. It includes three separate components, each serving a specific purpose in maintaining and repairing the car's braking system. The first component is a set of brake pads, which are essential for creating friction and slowing down the car when the brake pedal is pressed. The second component is a set of brake rotors, which are responsible for providing a smooth surface for the brake pads to press against. The third component is a set of brake sensors, which are designed to detect when the brake pads are worn down and need to be replaced. Together, these three components work to ensure the safe and effective operation of a car's rear brakes.