This method involves testing of the concentration of LH, a hormone that surges 24 hours before ovulation, to detect your fertile days.
Persona is a minicomputer that learns your menstrual cycle for the first month. During the next cycle, the monitor itself will tell you that you should do the test.
Bioself, on the other hand, works by analyzing temperature measurements.
Pros: Ovulation test kits are non-invasive. They are for women who do not want to use the classic contraception methods.
Cons: Your cycles must be regular. Any cycle disorders, a trip or even a minor infection may skew the results.