John Gill Commentary Exodus 28:4

"And these are the garments which they shall make: a breastplate, and an ephod, and a robe, and a coat of checker work, a mitre, and a girdle: and they shall make holy garments for Aaron thy brother, and his sons, that he may minister unto me in the priest`s office." — Exodus 28:4 (ASV)

And these are the garments which they shall make
Some for Aaron and some for his sons, some peculiar to the high priest, and others in common to him and other priests:

a breastplate, and an ephod, and a robe, and a broidered coat, a mitre,
and a girdle ;
of each of which, with others, there is a more particular account in this chapter, and will be observed in their order:

and they shall make holy garments for Aaron your brother, and his sons :
as those before mentioned, with some others not mentioned; some for Aaron only, and others that were to be worn by his sons also:

that he may minister unto me in the priest's office ;
these were absolutely necessary to the execution of the priestly office, and an essential qualification for it, and without which it was not lawful to serve in it.