How do I know which Beoplay or Beosound A9 variant I have?

The buttons and light indicators on the back as well as the type numbers* help you distinguish between the members of the Beoplay/Beosound A9 family:

Variant	Type number
Beoplay A9 1st Gen	2925-2929 2938-2939 2942 2944-2953
Beoplay A9 2nd Gen Beoplay A9 3rd Gen	2890-2896 3034-3038
Beoplay A9 4th Gen	3063-3075
Beosound A9 5th Gen**	3090

*Located on a label in the connection panel
** The light indicators are identical to the 4th Gen, but the 5th Gen can be identified by the USB-C socket in the connection panel.

How to find the serial number for my:

Beoplay A9 1st Gen

Beoplay A9 2nd Gen

Beoplay A9 3rd Gen

Beoplay A9 4th Gen

Beosound A9 5th Gen