What are ovulation test strips? Ovulation test strips are a testing tool used to detect ovulation in women. Its principle is based on the concentration changes of LH (luteinizing hormone) before and after ovulation. Ovulation test strips usually include an absorbent test strip and a testing window. The user needs to put the test strip into the urine collection container, and then put the test strip into the test window for observation. If there are two red lines on the test strip, it means that the LH level is elevated and ovulation will occur at 24-