You did not mention what do you want to know about them. The ovulation kits are useful to measure the time of ovulation in women. The tests are accurate only in few. These tests can be affected by some medicines especially hormonal medicines. Out of the available kits only the Clear Blue Easy Ovulation Test Pack has been found to be most reliable. The time of ovulation can be calculated in a woman if the periods are regular by the given link http://www.ovulation-calendar.net/. During the ovulation there are some cervical and mucosal changes in the woman, along with the increase in Basal body temperature. The ovulation kits are said to predict the Hormonal surge in the body. The Test kit allows you to detect this LH surge in your urine, and therefore tells you the 2 days when you have the best chance of conceiving. Fertility monitors help in detecting all the hormonal change that occurs before ovulation while ovulation prediction kits detect only one hormonal change.