these are backers. panes and booklets come wrapped in batches of 50 or 100, wrapped in celophane with a backer that holds them rigid. The backers are what you have, pressed into service as FDCs
i don't believe so
Note that the backers have become FDCs, so there are two arenas in which they could be considered: ephemera and FDCs
re: Need help to ID
these are backers. panes and booklets come wrapped in batches of 50 or 100, wrapped in celophane with a backer that holds them rigid. The backers are what you have, pressed into service as FDCs
re: Need help to ID
i don't believe so
Note that the backers have become FDCs, so there are two arenas in which they could be considered: ephemera and FDCs