Protection from light and metal (like the metal spring in the pump) are essential to preserving HOCl potency and stability. It is also essential to make HOCl at the right pH so that the concentration printed on the bottle is the same as the concentration inside the bottle. Products with concentrations that fall below .01% won't deliver the promised result. We provide a therapeutic concentration of HOCl and maintain the highest concentration over time of any leading brand. So you get the results you pay for