Built in PIR sensor/switch - The electronics used within this unit have been designed to detect the movement of body heat in order to activate the sensor. 30 second or 5 minute timer - Once the sensor has been triggered, this timer unit will automatically switch the connected lamps on for a period of 30 seconds (TSTI) or 5 minutes (TS) before automatically switching off. If continuous movement is detected then the lights in the vehicle will remain on.