tn The word is “their heads”; technically it would be “their capitals” (so ASV, NAB, NRSV). The bands were bands of metal surrounding these capitals just beneath them. These are not mentioned in Exod 26:37, and it sounds like the posts are to be covered with gold. But the gradation of metals is what is intended: the posts at the entrance to the Most Holy Place are all of gold; the posts at the entrance to the tent are overlaid with gold at the top; and the posts at the entrance to the courtyard are overlaid with silver at the top (S. R. Driver, Exodus, 387, citing Dillmann without reference).
sn For a good summary of the differences between the instruction section and the completion section, and the reasons for the changes and the omissions, see B. Jacob, Exodus, 1022–23.