The Clearblue Digital Ovulation Test It works by detecting the rise of the ovulation hormone LH 24-36 hours prior to ovulation and identifies the 2 best days to conceive in a given cycle. Making love during these 2 days gives you your best chance of conceiving. Is 99% accurate at detecting your LH surge The easy to use, natural and non-invasive urine test has a unique flashing test stick symbol to show you the test is working. Youll get your results in 3 minutes. This pack contains 10 tests.