Fertility monitors.. Has anyone used these??

Nicole
So I'm 32 and have been trying for 6 months with no luck.. My friend let me borrow her clear blue fertility monitor..  It's $200 so I'm glad she let me borrow it but has anyone tried these? After 2 months of using it she became pregnant.  According to the monitor yesterday and today are my peak days so hoping for the best! Thanks for ur help!