Clearblue Tests Refills for Fertility Monitor contains 20 fertility tests and 4 pregnancy tests. The fertility tests are for the Clearblue Advanced fertility monitor and the Clearblue fertility monitor. They are reliable at 99%. The pregnancy tests are to use only with the Clearblue Advanced fertility monitor. They are reliable at 99%. Most of women need 10 tests per cycle. If you have long irregular cycles, you can need 20 tests.