Leica fact 24: Leica boxes may be used to determine the age of an accessory.
Leica collectors often have difficulty in determining the age of an accessory. It is easy to find websites with serial numbers and production years for Leica cameras and lenses. With that information it is quite easy to determine the production year of cameras and lenses.
This is different for accessories. Firstly most accessories don’t have a serial number, and if they have one, no public sources are available to find a production year for these serial numbers.