I posted this already elsewhere, but thought it was about Top Bars so here it is:
And here is how you measure it:
Just to show some measurements. Here is the first brood comb I found in my Top Bar Hive today. To measure, start at the 10mm mark and count over 10 cells. Looks like 4.7cm for ten cells to me. That's 4.7mm. When the bees are flying I'll try to actually look through the hive for some smaller ones.
I put a package of large cell Carniolans in this hive in the Spring 2004. There was no comb just bar top bars. I have swapped no comb out.