Fan and fixture pan box with adjustable mounting bracket for wood I-Joists in existing construction. Heavy-duty, plated steel fan/fixture box with fully adjustable mounting bracket. For retrofit installations on wood I-beams or rafters set 16 to 24 inch on-center. No parts to lose installation and adjustment screws ship parked in place. Installs quickly and securely on wood I-beams. Position the box anywhere along the bracket to center the fan/fixture in the room.