I have begun the use of CircO2. I am usually skeptical of such products and their claims -- frequently having to take advantage of 90-day returns. Sometimes, of course, varying circumstances make it difficult to determine whether a product or other factors are the contributors to change. However, I am currently cautiously optimistic that CircO2 is having beneficial effects. On THIS product, I will not be using the 90-day return policy! Since I've just now completed 30 days of use, the jury is yet out. But sometimes the jury knows in advance.