John Gill Commentary Exodus 26:10

"And thou shalt make fifty loops on the edge of the one curtain that is outmost in the coupling, and fifty loops upon the edge of the curtain which is [outmost in] the second coupling." — Exodus 26:10 (ASV)

And you shall make fifty loops on the edge of the one
curtain, that is outmost in the coupling
Just in like manner, and in the same place where they were ordered to be put on the linen curtains, only these are not said to be of blue, but perhaps were wrought with goats hair:

and fifty loops in the edge of the curtain which couples the second; these loops were set on each of the curtains where the two large pieces were to be coupled together.