Numbuzin No.5+ Vitamin Concentrated Serum is a highly effective vitamin brightening serum featuring key ingredients like glutathione, niacinamide, alpha-arbutin, and tranexamic acid. Glutathione is a powerful antioxidant that works in synergy with many vitamins to build a stable and effective antioxidant network that maximizes its effect. It is clinically proven to improve the appearance of outer-skin melanin, under-skin melanin, skin tone and brightness after just 2-4 weeks.