Build up existing flange when added subfloor, tile, etc., leaves flange at or below floor level stack rings for additional height designed to replace rusted or broken metal swivel rings without replacing the plastic portion of the flange closet flange extension ring builds up existing flange when adding subfloor, tile, etc. Leaves existing flange at or below floor level can be stacked if needed.7/16 inch stackable ring,7/16 inch stackable ring,Used to raise height of closet flange,Can be stacked if needed