The double concentrated serum Intensive VITAMIN C² combines 2 forms of vitamin C for an immediate and continuous action on dark spots and brightness, in una 100% fresh formula: . Pure vitamin C at 10% or ascorbic acid for immediate effectiveness. This is preserved until the first use thanks to the double compartment bottle that allows for una optimal storage of the formula. . 2% provitamin C or ascorbyl glucoside for continuous effectiveness. Clinically proven effectiveness* against spots and brightness: After 14 days: -17% spots, +23% brightness, and +23% smooth skin. After 28 days: -29% spots, +44% brightness, and +48% smooth skin. After 42 days: -45% spots.