the La Roche-Posay Pure Vitamin C10 Serum, which is often marketed as an ultra-concentrated serum because of its high potency in delivering the benefits of pure vitamin C (ascorbic acid) directly to the skin. This serum is designed to address dull skin, uneven skin tone, and fine lines by harnessing the power of vitamin C to brighten the complexion, even out skin tone, and combat early signs of aging.