Clear & Simple Ovulation Test Strips allow you to identify when you're most fertile and likely to get pregnant by detecting the sudden LH surge in urine that occurs 24-48 hours before ovulation. The test is easy to use and read: simply immerse one of the test strips in a urine sample for at least 10 seconds and wait for the coloured line(s) to appear. A positive result (i.e. that an LH surge has been detected) is indicated by the appearance of two coloured lines, whilst a negative result is indicated by the appearance of only one coloured line. Results are 99% accurate. The packet contains 5 ovulation test strips.