The stem will be provided in assorted colors, and the stem is new stock from Unicomp which works on both Model M and Model F keyboards - you can't pick the color.
The relegendable caps allowed banks to put in specific function keys before the days of the GUI for IBM mainframes and terminals.
This is the only place to get these IBM-style reproduction transparent caps, unless you buy an original 4704 keyboard that happens to have these caps (if you can find one!).
You can access a template for printing your keys here: https://deskthority.net/workshop-f7/ibm-4704-model-f-model-m-transparent-key-template-t9794.html