C-15 Serum is a highly potent, absorption-enhanced Vitamin C serum, formulated with 15% acid Vitamin C, and crafted to support collagen production and help with the signs of aging and dark spots. This formula promotes the brightening and evening of the skin tone, while helping to protect the skin from environmental stressors and photo-aging. Featuring L-Ascorbic Acid, Vitamins C and E, and Hyaluronic Acid, the C-15 Serum is rich in supportive sun-protective care and hydration. Added to a routine, results are best if applied to a clean face and neck, and given 10-15 minutes to settle into the skin before following with additional products.