The concept is good but the app and website information is lacking. The test results are confusing and the app doesn't offer any additional explanation to help you understand. I had to manually set my peak days because the LH results were slightly under what the app shows as a positive. If I hadn't done that the app would not have told me to take the PDG test. I also could not change the dates of my period so the dates are off. Lastly it would be nice to be able to see what is coming up the next day for what test to take. I have to look at the app when I wake up, before going to the bathroom to confirm if I need to pee in a cup or not.