Chi Iron Guard Thermal Protection Spay is always on our top selling list because it does so much to protect hair from the damage that flat irons and curling irons as well as hair dryers do to your hair. When the vital moisture barrier on the cuticle is stripped you have can have lasting hair damage. This product is top of the line - best in class when it comes to protection against the damages and dryness, frizzies and more that heat and styling cause to ones hair.