coupled together from bottom to top and fitted into a single ring. These will serve as the two corners.
KJV
And they shall be coupled together beneath, and they shall be coupled together above the head of it unto one ring: thus shall it be for them both; they shall be for the two corners.
ASV
And they shall be double beneath, and in like manner they shall be entire unto the top thereof unto one ring: thus shall it be for them both; they shall be for the two corners.