This kit is just an expensive thermometer! I tried it and am in the process of getting a refund. The patch fell off after 3 hours. Luckily, I felt it fall off so was able to retrieve it [I was in a shop] so did not have to pay extra for a new one. I reapplied it and It fell off again the first night I wore it! I complained and was sent a hefty and unattractive armband. The supposedly high-tech device that comes with it is complicated and difficult to use. I gave up with it and entered my data using the software instead and no 'specialist' analysed it or contacted me. I was contacted after 3 weeks, however, by the Duo Fertility admin people who informed me that my patch was faulty and they were sending me a new one. I used the new one for a week. I finally realised after a month of wearing the stupid device that neither patches had recorded a single temperature for the entire month I'd been using them! What a waste of time and money! I can't believe this is being hyped as a revolutionary product! It's just a very poor and expensive thermometer!