The DEI 508D Dual Zone Motion Radar Sensor is a highly sensitive car alarm accessory that detects motion inside and outside your vehicle. It includes two radar sensors that cover different zones, providing comprehensive protection against theft and break-ins. The system can differentiate between large and small movements, ensuring that false alarms are minimized. When the sensors detect any motion, the car alarm is triggered, and a loud siren is activated to deter potential thieves. With its advanced technology and reliable performance, the DEI 508D Dual Zone Motion Radar Sensor is a great investment for those looking to enhance the security of their vehicle.