John Gill Commentary Numbers 4:12

"and they shall take all the vessels of ministry, wherewith they minister in the sanctuary, and put them in a cloth of blue, and cover them with a covering of sealskin, and shall put them on the frame." — Numbers 4:12 (ASV)

And they shall take all the instruments of ministry ,
wherewith they minister in the sanctuary
The garments in which the priests, ministered in the sanctuary, which were laid up in proper places, and which they only wore when in service:

and put [them] in a cloth of blue, and cover them with a covering of
badgers' skins ;
all wrapped up in one bundle:

and shall put [them] on a bar ;
the same sort of carriage on which the candlestick and its vessels were borne, (See Gill on Numbers 4:10).