Numbers 4:6

They are to place over this a covering of fine leather, spread a solid blue cloth over it, and insert its poles.

Note Possibly the hides of large aquatic mammals; also in verses 8, 10, 11, 12, 14, and 25; see Exodus 25:5.

And shall put thereon the covering of badgers’ skins, and shall spread over it a cloth wholly of blue, and shall put in the staves thereof.

put a covering of sealskin on it, spread a blue cloth over it, and put in its poles.

and shall put thereon a covering of sealskin, and shall spread over it a cloth all of blue, and shall put in the staves thereof.