Exodus 26:4-6

And thou shalt make loops of blue upon the edge of the one curtain from the selvedge in the coupling; and likewise shalt thou make in the edge of the curtain that is outmost in the second coupling. Fifty loops shalt thou make in the one curtain, and fifty loops shalt thou make in the edge of the curtain that is in the second coupling; the loops shall be opposite one to another. And thou shalt make fifty clasps of gold, and couple the curtains one to another with the clasps: and the tabernacle shall be one whole.