The Levitical High Priests wore an Ephod over the priestly robe and under his breastplate. It is described in Exodus 28 - 35. On top of the shoulders the Ephod was fastened by two onyx clasps. Twelve gem stones on the breastplate contained the name of the 12 tribes of Israel. The Ephod was prominently displayed in the Tabernacle. The Ephod is intricately tied to worship (Exodus 28:1).