A synthetic form of vitamin C that is fat soluble; penetrates the skin very easily. Ascorbyl Tetraisopalmitate is made by taking the natural Vitamin C molecule and attaching 4 extra molecules to the corners of the Vitamin C molecule. This new molecule, called Ascorbyl Tetraisopalmitate has a number of important advantages. It is lipid soluble just like your skin which means that it easily penetrates into the skin. It does not require a low pH to get it to penetrate the skin so it does not sting. It stimulates your skin to make its own natural moisturizers called glycosaminoglycans. Glycosaminoglycans will allow your skin to absorb moisture from your body which reduces the need for applying other moisturizers. It is stable in air and water for up to 18 months which means it will work as an anti-oxidant long after you start using it.