The door open module is an optional accessory for all the UBITracer ZT-Series devices. 
This module does not have a serial number and is interchangeable between devices. 
The door open module is designed to detect door-opening events therefore enhancing security.
Proper installation is required for the module to function.
This module cannot be used by itself. It does not produce warning sounds or light. 
Good cell signal condition and a functioning ZT-Series device attached correctly are needed for this module to achieve its intended purpose.
UBITracer is not responsible for compensating lost cargo.