I have used this product for a few months. The first several boxes of testing sticks worked fine. The last box I purchased did not. There is an area on the stick that is supposed to show blue, after urinating. About 20 of the 30 sticks did not do so in this box. Now the accuracy of my monitor is incorrect, because it is not reading several of the sticks. I feel like that particular box was a waste of money, and has hindered the rest of my monitoring. I have no problem with this product, just this particular box of testing sticks!