Gloria,
I am so happy for you. Your hatch is going so well!!
Justino, You don't have to use one of those...it just makes it easier knowing the temp in egg is right. You can also make your own water wiggler by putting water in a heavy duty quart size zip-lock bag (don't fill it completely full). Then fold it over in half and put a couple of rubber bands on it to hold it in the shape of a tube. You put your probe in between the folded over layers...or put it in before folding it over.