Clearblue Ovulation Test Digital will help you determine the optimal four days for pregnancy, twice as effectively as other tests. By detecting elevated levels of the ovulation hormone LH (luteinizing hormone) 24-36 hours prior to ovulation, it identifies the two most fertile days in your menstrual cycle. Having intercourse during these days offers the best chances of conception. With clear digital results, there is no need to interpret color bands, and it comes with 10 test sticks. Its ability to detect LH increases makes it highly effective.