111Skin Y Theorem Repair Light Serum NAC Y2 in Beauty: NA. 111Skin Y Theorem Repair Light Serum NAC Y2 in Beauty: NA. A lightweight alternative to the original Y Theorem Serum, this formula delivers the same unrivalled benefits but with a lighter, fluid texture that's ideal for humid conditions or those with oily skin. Packed with incredible antioxidants and brightening agents to boost collagen production and reduce facial creasing, this powerful anti-aging serum reveals a hydrated, restored, and radiant complexion.. Calendula extract heals and soothes the skin. Amino acids improve skin elasticity. Aminocaproic acid heals, prevents scarring, calms, and soothes the skin. 1.01 fl oz. Massage serum sparingly onto the face and neck with a gentle patting motion. Follow with the Space Anti Age Day Cream or Nocturnal Eclipse Recovery Cream and Space Defence Bright Eye Lift Gel. 111R-WU25. YTL30. Working in collaboration with space scientists responsible for the well-being of astronauts, renowned cosmetic surgeon Dr. Yannis Alexandrides developed the patented NAC Y2 formula that runs through the core of his highly effective skincare line. Named after his Harley Street, London clinic, 111SKIN's cutting-edge products feature potent healing ingredients designed to promote a youthful and radiant appearance while offering unprecedented protection against environmental damage.