John Gill Commentary Exodus 28:14

"and two chains of pure gold; like cords shalt thou make them, of wreathen work: and thou shalt put the wreathen chains on the settings." — Exodus 28:14 (ASV)

And two chains of pure gold at the ends
The use of which was to hang the breast plate on, after described; one end of them was fastened to rings on the ouches in the shoulder pieces, and the other end to rings on the breastplate, and thus it hung:

of wreathen work you shall make them ;
these chains were not made after the manner of circles or ringlets coupled together, as chains usually are, but of golden wires twisted together as a rope is twisted

and fasten the wreathen chains to the ouches ;
to the ouches on the shoulder pieces of the ephod, in which the onyx stones were set, very probably to rings that were in these ouches.