The oil powered technology propels colorants deep into the hair, without ammonia, giving you pure, vivid, long-lasting color. Olia visibly improves and restores hair as the oils help to reverse roughness and dullness for more brilliant, long-lasting color. Hair is Hydrated, Silky and up to 3X Shinier than unwashed, uncolored hair. Garnier Olia shade 4.0, "Dark Brown," is a natural brown shade that is one shade lighter than Olia shade 3.0, "Darkest Brown." It provides 100% gray coverage and is best for anyone with natural hair between light brown and black.