Exodus 36:24-28

and he made forty bases of silver under the twenty boards; two bases under one board for its two tenons, and two bases under another board for its two tenons.

Then for the second side of the tabernacle, on the north side, he made twenty boards,

and their forty bases of silver; two bases under one board, and two bases under another board.

And for the back of the tabernacle, to the west, he made six boards.

He made two boards for the corners of the tabernacle at the back.