By connecting the earbuds to the Panasonic Audio app, you can enjoy:
Open the Panasonic Audio Connect or the Technics Audio Connect app and then select "Headphone information""
When you are at the headphone information section, you will be able to update the firmware of the earbuds and you can also find out what your current firmware's version is.
This FAQ applies to models RZ-S300, RZ-S500, EAH-AZ70