I've been using the ovulation strips and was driving myself crazy with whether or not the control line was as dark or darker than the test line. So I decided to bite the bullet and pay the $50 bucks for the Clearblue digital ovulation test. But thennnnnn I start reading that even though Clearblue tells you to use your FMU, that would cause the test to show you are in your fertile window and if you retested few hours later, the happy face on the test you once saw would turn into just a O meaning you are not in your fertile window. ANNOYED much?!?! So my first test was yesterday evening. It showed O. So then I took one this morning and I got the happy face. But ofcourse I was doubting it so I waited 4 hours to retest. I was expecting to get the O I got the first time. But I got another smiley face. Sooooooo I guess they do work?!?