Exodus 36:11-13

He made loops of blue on the edge of the outermost curtain in the first set; he did likewise on the edge of the curtain that was outermost in the second set. He made fifty loops in the one curtain and he made fifty loops on the edge of the curtain that was in the second set; the loops were opposite each other. He made fifty clasps of gold and joined the curtains to one another with the clasps, so the tabernacle was a unit.