I have several of these old style Akro-Mils parts cabinets hanging in my shop. AFAIK the drawers and dividers are not interchangeable between these and the current production Akro-Mils cabinets. The original dividers these came with leave a little to be desired in terms of fit, and they never came with enough of them in the first place.
There is a double thickness area at the top of the divider, mainly to add some stiffness but it's also a good place to write the bin contents with a marker.
This was drawn in inch dimensions because the original parts were designed that way and it was just easier, so you will need to tell your slicer to convert.
See also:
https://www.printables.com/model/317738-mini-bin-for-akro-mils-10-115
The author marked this model as their own original creation.