Identity a specific Keypad 2 if you have multiple?

I have 3 Keypad 2. When they were last charged they may have been mixed up. How do I easily identify them? There are no serial numbers or keypad specific info in the app that I can find.

Only thing I can think to do is arm away and trip the system with motion at each keypad. Is their a less annoying way? Seems strange that there isn't a serial or is number in the app