Exodus 26:4-6

You shall make loops of blue on the edge of the outermost curtain in the first set, and likewise you shall make them on the edge of the curtain that is outermost in the second set. You shall make fifty loops in the one curtain, and you shall make fifty loops on the edge of the curtain that is in the second set; the loops shall be opposite each other. You shall make fifty clasps of gold, and join the curtains to one another with the clasps so that the tabernacle will be a unit.