The poles are to be inserted into the rings so they will be on two sides of the altar when it is carried. (NIV)
The poles shall be put through the rings on the two sides of the altar, with which to carry it. [Num. 4:14, 15.] (AMP)
And the staves shall be put into the rings, and the staves shall be upon the two sides of the altar, to bear it. (KJV)