Double White Tube A: Vit C Serum 11S Stable 11% Vitamin C Tube B: Azelaic 20 Azelaic Acid 20% Advanced Intensive System For Comprehensive Whitening Treatment Double White includes a combination of Vit C Serum 11S (11% of the Derived Stable Vitamin C), Azelaic 20 (Azelaic Acid 20%) and Alpha Arbutin (5%). This powerful blend helps reduce discoloration, evens out skin tone and protects the skin structure from free radicals. The additive DermShieldTM allows the use of the cream without causing irritation.