Marten bites can cause costly damage to vehicle components and thus shut down important functions. The effectiveness of an existing marten defense system can be increased with the installation kit for expanding the marten defense. The battery-operated high-voltage device with double-pole stainless steel contact plates is expanded by 2 further high-voltage plates. An electrical connection to the vehicle electrical system is not required. In order to protect the animal in defense, additional ultrasound tones are emitted.