Some wire excluders have a bee space top and bottom which means that there can be a double space on one side or the other depending on whether you have a top space hive or a bottom spaced one.
(I have a WBC brood box which has a top bee space and as I only have wire excluders for my WBC's, that box invariably gets drone brood between the brood box top bars and the excluder in the summer).
(I have a WBC brood box which has a top bee space and as I only have wire excluders for my WBC's, that box invariably gets drone brood between the brood box top bars and the excluder in the summer).
May your bees read the same books as you do.