I used a small digital indoor outdoor thermometer (Lowe's garden section for $8 I think) with the wire probe going into the door (no drilling, so if it don't work for you it isn't perminant) and the selector on outdoor tells you the temp in the frdge. It is small and comes with velcro so it can be attached easily to the outside of the fridge, mine also has a light and the hotest/coldest memory so you can judge fluxuations in the cooling. I hope this is what you were asking about. Lowe's or Home Depot should has a bunch.