Nioxin Density Defend Diaboost Hair Thickening Serum is perfect for those with thin, fine hair types looking for thicker, fuller looking locks. The leave-in treatment is enriched with active ingredients that coat every strand of hair, thickening the hair at the roots. Powered by HTX technology that contains ingredients such as Caffeine and Niacinamide that leaves the hair instantly fuller-looking, while also protecting against hair breakage. This provides a healthy scalp environment for the hair to grow longer. The nourishing ingredients also penetrate the hair, making it more manageable for styling.