A keratin-infused hair milk (likely a leave-in treatment) designed to nourish, strengthen and smooth hair.Are lightweight creamy leave-in treatments you apply to damp hair.Contain keratin (a hair-strengthening protein) and conditioning ingredients.Help hydrate, reduce frizz and improve manageability.Leave hair feeling softer and smoother without heaviness.These types of keratin milks are commonly used after washing before styling to help protect hair and make it easier to comb and style.