Abstract: Structure is provided for pivotally mounting a box used to guide a bar through the rolls of a rolling mill. The guide box is aligned with a guide bell, and the two are mounted in such a relation that cobble forces transmitted to the guide bell are absorbed by the mounting structure and are not transmitted to the guide box or to the bearings which mount the guide box for pivotal movement. In its operative position, adjacent the rolling mill rolls, the guide box is accessible for adjustment and most maintenance work, and the upstream and downstream ends of the guide box are readily visible. The guide box may be pivoted away from and returned to precisely the same operative position, time after time.