Well as at this exact moment in time, I'm the fourth person to write a review on these. And in complete contrast to the other three, I have to review them as being a complete and utter waste of money! They don't work! Now I don't say this flippantly...my opinion is based on the following: I won't name names, but I have been on a commercial ketogenic diet plan for the last 4 weeks, and have stuck to it religiously. I have been "in ketosis" for the majority of this period (detected via various manual methods as advised by my plan consultant) and I'm happy to say, the weight has been falling off! However, in all that time, I have never had a single positive result. Of any grade on the scale! Although I always test the first urine of the day, I thought it might be that my urine was too dilute, as I drink somewhere around 3.5 litres of water a day. So for four days, I hardly drank anything, then did a test, and it was still negative. Having my suspicions about the accuracy of the tests, I then ordered a box of Ketostix (which I should have just gone ahead and done to begin with, rather than trying to save a couple of pounds by going generic) and hey presto, first test out of the box (done alongside one of these) was a positive result, against yet another negative from these. And so was the case for the whole of the next week I dual tested. They were sealed and in tact when I got them, and I kept them tightly sealed throughout. Perhaps I just got a duff batch, who knows! But my advice, if you really want to get an accurate result, go for the brand name, because there's a heck of a difference in quality, for the sake of a couple of pounds!