I used this item for several months and got to realize that it always indicates the fertile days based solely on your cicle length. It's a lie that it measures electrolytes in your saliva to detect the fertile days.I used this and another ovulation detector at the same time and the OvaCue kept telling me that my fertile and peak days were between day cycle 12 and 17. The other one said I was on fertile days...but not marked any peak until day 28, when it detected the ovulation day (I had irregular cicles during the last 3 months and the OvaCue always said my fertile days were from 12 to 17). Finally I got pregnant that very long cycle on day 28 or 29 (which I confirmed on day 30 with a raise in my basal temperature). Obviously, had I kept using the OvaCue I had never gotten pregnant. So, don't waste your money and invest in a serious fertility monitor (the other one I used it for only two months, the second one I got pregnant).Thank you.