Exodus 38:3-7

3He made all the utensils for the altar: the pans, the shovels, the basins, the forks, and the firepans; all its utensils he made of bronze.

4And he made a grate of bronze network for the altar, under its rim, midway from the bottom.

5He cast four rings for the four corners of the bronze grating, as holders for the poles.

6And he made the poles of acacia wood, and overlaid them with bronze.

7Then he put the poles into the rings on the sides of the altar, with which to bear it. He made the altar hollow with boards.