This part supports the chimney on a slab, floor or joist. It makes it possible to maintain a 2" clearance between the chimney's outer casing and combustible materials in its path. A tightening collar locked around the chimney and secured by self-taping screws (supplied) rests on a horizontal plate screwed or nailed to the floor or slab, which can serve as an intermediate support. (Refer to chart for loadbearing capacity.)