Exodus 26:4-6

And you shall make loops of blue on the edge of the outermost curtain in the first set. Likewise you shall make loops on the edge of the outermost curtain in the second set. Fifty loops you shall make on the one curtain, and fifty loops you shall make on the edge of the curtain that is in the second set; the loops shall be opposite one another. And you shall make fifty clasps of gold, and couple the curtains one to the other with the clasps, so that the tabernacle may be a single whole.