וְעָשִׂיתָ֮ שְׁתֵּ֣י טַבְּע֣וֹת זָהָב֒ וְנָתַתָּ֣ה אֹתָ֡ם עַל־שְׁתֵּי֩ כִתְפ֨וֹת הָאֵפ֤וֹד מִלְּמַ֙טָּה֙ מִמּ֣וּל פָּנָ֔יו לְעֻמַּ֖ת מֶחְבַּרְתּ֑וֹ מִמַּ֕עַל לְחֵ֖שֶׁב הָאֵפֽוֹד׃
And thou shalt make two rings of gold, and shalt put them on the two shoulder-pieces of the ephod underneath, in the forepart thereof, close by the coupling thereof, above the skilfully woven band of the ephod.
Read kabbalistic (mystical) interpretation of Exodus 28:27: and classical mystical sources.