Some of those devices have a rotary locking setup, and they have a special key to unlock the cover- - - - -that were usually only given to dealer shops. I believe the name of that system was "armor-flex" or something similar. It wasn't impossible to defeat, but it would certainly slow a car thief down long enough to point a shotgun at his backside!
Here's an example of the complete assembly- - - -including the lock tumbler and key:
www.ebay.com/itm/335941991327?Jerry
