The Zimmermann Brake Kit - Front/Rear - 138878 is a comprehensive kit of products designed to service the brakes of a car. It includes various components that are essential for maintaining the functionality and safety of the braking system. The kit contains a set of front and rear brake pads, which are responsible for creating friction against the rotors to slow down or stop the vehicle. It also includes front and rear brake rotors, which are the discs that the brake pads press against to create the necessary friction. The kit also contains front and rear brake sensors, which are responsible for monitoring the condition of the brake pads and alerting the driver when they need to be replaced. Additionally, the kit includes front and rear brake hardware, which consists of various small components such as clips, bolts, and pins that are necessary for the proper installation and function of the brakes. Overall, the Zimmermann Brake Kit - Front/Rear - 138878 is a complete package of essential brake components that are vital for maintaining the safety and performance of a car's braking system.