Exodus 26:5

Fifty loops shalt thou make in the one curtain
In the first great curtain, or in the outermost of the five that were sewed together: and fifty loops shalt thou make in the edge of the curtain that is in
the coupling of the second;
as many also were to be made in the outermost of the second great curtain where it was to be coupled with the first: that the loops may take hold one of another;
or rather that they might answer to one another in both curtains; for the loops could not take hold of one another, only were made to meet together by the taches, hooks, or clasps put into them, next mentioned.