From TTC:

Hi Ladies. I'm new to this board but not new to the site. I've got 2 kids and I'm trying for a third. I picked up the CBEFM and have a question for those who have used it....

Do the test sticks have to be from the same batch? I know people have given others leftovers. Will that screw anything up? This will be my first month using it.

Just trying to save a little $$ if I can.

TIA! and