It's a fabulous product...am glad I used the 22% instead of 35% which is also offered because my teeth are sensitive, and while there is a small amount of increased tooth sensitivity with this product, it is well worth having, as my teeth brightened several shades within a week; now I just use it around once or twice a week for maintenance, but my family and friends have all complimented me...as a matter of fact, my husband used some, and the difference was immediate and noticeable. Not only will I purchase this product again, but I will purchase it from the same seller who did a breathtaking job, getting it to me in record time!