This is the Directed 507M digital tilt sensor, also known as the DUB1.

Most alarm sensors watch for impact. A tilt sensor watches for the vehicle changing angle, which is what happens when someone jacks it up to take the wheels, or winches it onto a flatbed. Those thefts are silent and quick, and a shock sensor often never fires.

The 507M is a digital sensor rather than a mechanical one, so it measures the change in angle rather than relying on a ball or a bead of mercury to move. That means fewer false alarms from a windy day or a sloped driveway, and it works in any mounting orientation.

Contains no mercury, which matters where local rules restrict it.

Simpler mechanical alternatives: the Directed 8613 ball bearing and the HE-7854 mercury switch.