Product review (4 stars): Edited: Changed the rating
I bought one of these and liked it so much I ordered another one. The second one is of no use to me unless someone can tell me how to change from Celsius to Fahrenheit. I read in the questions and answers above that there should be two holes on the back. Well, the first one I bought had little buttons to change from C to F but the second one, the one I received today does not. And it also does not have the  "two little holes" someone mentioned it should have. I'd return it if I could but unfortunately there are no returns for this. (I tried.)

Edit: Okay, after much fiddling around with the thing I discovered there is a plastic piece surrounding the battery cover that can be carefully popped off... there is a little button there to change from C to F.