The volumetric anti-theft device is able to detect a physical intrusion inside the passenger compartment and is made up of passive infrared sensors that are able to perceive the temperature of a human being when he enters the range of action. As soon as the infrared detects movement, the acoustic signal is activated.

This device does not need remote controls or various systems to activate it but is activated as soon as the Defender Car Security Steering Lock is inserted and the doors are closed. To deactivate, the reverse sequence is followed.
The anti-theft device is equipped with further modules: anti-collision sensor, anti-lifting sensor and the anti-starting module.