OPK
WHAT: An ovulation test detects the LH surge in urine, signaling that ovulation is likely to occur in the next 24-36 hours. Having intercourse within 24-36 hours after detecting the surge can help maximize your chance of becoming pregnant.
HOW: Glow recommends the First Response™ Ovulation Test Kit. It maximizes your chances by accurately predicting your most important fertile days based on directions for use.

Over 99% in detecting the LH Surge in Laboratory Studies.