Jeremiah 52:20-21

20The two pillars, the one sea, and the twelve brazen oxen that formed the bases, which king Solomon had made for the house of Jehovah: for the brass of all these vessels there was no weight.

21And as to the pillars: the height of one pillar was eighteen cubits, and a line of twelve cubits encompassed it; and the thickness thereof was four fingers: it was hollow.