Intelligent Nutrients Curly Hair Serum 3.75 fl oz. A hair serum for defining curls. Intelligent Nutrients Curly Hair Serum reduces frizz and flyaways in curly hair for a voluminous and sharp appearance. Managing the unmanageable, ingredients like grapeseed oil and larch tree resin moisturize your strands while providing a light hold that won"t weigh down your hair. Most suitable for frizzy and curly hair.