Kahl Felt Hat Stiffener is used by professional hat makers to add shape and body to felt hats. The contents include "denatured alcohol" and "natural resinous glaze." Gentle on tone and texture of hats without yellowing and flaking associated with other stiffeners. Versatile enough to use on any quality of hat without affecting shaping and/or cleaning at a later date. Will not leave chemical residue when applied to a hat. Environmentally friendly and will not harm felt or fabric.