Maximize the chances of conceiving naturally. Pinpoints your 2 most fertile days. #1 OB-GYN recommended brand. This test detects a hormonal surge (LH, Luteinizing Hormone) in your urine, which occurs prior to ovulation. Make love at any time in the next 48 hours starting from the first 'smiley face' to maximize your chances of becoming pregnant naturally. In a study, the unmistakably clear digital results gave an accurate reading. Over 99% accurate at detecting the LH surge. Hormones are a more accurate predictor of ovulation than Basal Body Temperature, which only changes after ovulation. Contains: 1 test holder; 7 test sticks; 1 English/Spanish insert.