MD Ultimate Stem Cell Factor is by far the best product that I have ever used. It goes on easily and instantly tightens my skin, increases elasticity and firmness. Stem Cell factor has improved the area around my eyes, on my neck and decollete as well as my face. The key with Dr. Lin's product is that it has a high percentage of active stem cell factors, 55%, which regenerate the skin. I have experienced dramatic visible results from using MD Ultimate stem Cell Factor.