So are there two trays stacked per package? I see one with 10 rows of 12 primers and one with 10 rows of 13 primers, a total of 250. Then why the spacer?
Yes, there are 2 trays per package. I have no idea about spacers, but I’d guess it is original.
The spacers are there to fill the partially empty slots because of the uneven number (13) in each row.
F.A. packaged the primers in a lot of different sized cartons. All that I have seen makes me think that they needed a little more thought put into the carton design.