I have a hodgepodge of different panels from one-eighth to one-quarter inches in thickness which means I need spacers of varying thickness. I ordered online inexpensive one-eighth inch thick balsa panels cut to size, but I requested a cut smaller than the actual size of the art panels. This smaller cut assures me that none of my spacers could be larger than my art panels. Also, the multiple layers give me the flexibility to raise or lower the art panel in a floater frame to within one-eighth of an inch below the face of the floater frame.