The Iles Formula Finishing Serum is the hair's best protector against heated tools + UV + color fade + humidity, without ever weighing the hair down. It can be used on both wet hair before drying, and on dry hair too to tame down any frizz. It is exceptional when heat activated, e.g. when blow-dried into the hair. It works like magic, making thin hair feel organically thicker, and calms down thick, bushy hair. Please be sure to apply to each section about 1 inch from roots to ends.