John Gill Commentary Numbers 4:11

"And upon the golden altar they shall spread a cloth of blue, and cover it with a covering of sealskin, and shall put in the staves thereof:" — Numbers 4:11 (ASV)

And upon the golden altar they shall spread a cloth of blue ,
&c.] The altar of incense, which was overlaid with gold, and therefore called a golden one, to which the allusion is in (Revelation 8:3) ;

and cover it with a covering of badgers' skins ;
after the cloth of blue was spread upon it:

and shall put to the staves thereof ;
into the rings, both made to bear and carry it, upon occasion, from place to place.