There are Japanese version (mild) and US version (strong)! Those with particularly sensitive skin can choose the Japanese version, and after adapting, you can try the US version as needed! Japanese version C5 12ml $275, Japanese version C10 12ml $340 Japanese version C10 26ml $550, Japanese version C20 15ml $640 Japanese version C25 12ml $750 US version C10% 30ml $490, US version C15% 30ml $560 US version C20% 30ml $640. [C10 Benefits] Improves early signs of skin aging such as spots, dull complexion, enlarged pores, oiliness, and acne. Promotes healthy skin cell regeneration, restoring even, fair, radiant, and smooth skin texture. [C20 Benefits] 3 times higher penetration than the original formula. Delivers highly concentrated "pure vitamin C+E" for powerful antioxidant and anti-aging effects into the dermis.