Increases the diameter of each existing hair strand HOW IT WORKS: NIOXIN Diaboost with HTX, a fusion of Niacinamide, Panthenol & Caffeine, is proven to: 1. Boost your existing hair diameter instantly. 2. Penetrate hair & make it manageable & full. 3. Thicken existing hair at the roots SO IT IS AS IF YOU HAVE UP TO 11, 000 MORE HAIR STRANDS! Diaboost is a leave-on treatment that can be used with the Nioxin 3-part systems for thicker, denser-looking hair. Directions: Apply generously throughout the scalp. Massage gently at the hair roots. Do not rinse off.