Sadoer Whitening Serum Dark Knuckle Niacinamide + Vitamin C 50ML is a potent skin‑brightening serum designed to target dark knuckles, pigmentation, and uneven skin tone. Formulated with niacinamide and vitamin C, this lightweight serum helps boost radiance, fade dark spots, and improve skin texture while providing hydration. Perfect for daily use on areas with stubborn darkness for a brighter and more even complexion