Exodus 38:6-8

Young's Literal Translation

⁶ and he maketh the staves of shittim wood, and overlayeth them with brass;

⁷ and he bringeth in the staves into the rings on the sides of the altar, to bear it with them; hollow [with] boards he made it.

⁸ And he maketh the laver of brass, and its base of brass, with the looking-glasses of the women assembling, who have assembled at the opening of the tent of meeting.