Charles Ellicott Commentary Exodus 28:23

"And thou shalt make upon the breastplate two rings of gold, and shalt put the two rings on the two ends of the breastplate." — Exodus 28:23 (ASV)

Two rings on the two ends —that is, on the two upper corners of the breastplate. The chains were to be passed through the two rings, which they were then to unite with the “ouches” of the ephod. (See Exodus 28:13-14.)