The Walkerduct Pro Series of underfloor duct junction boxes are equipped with nonmetallic corner inserts that provide a controlled cable bend radius around the box`s internal tunneling. The boxes come with square or round cover plates. Square boxes include flangeless aluminum trim to accommodate 1/8-inch tile. Round covers are generally less visually intrusive in patterned carpet applications. Heavy-duty junction boxes are suitable where heavy loads are transported across floors.