I bought one of these and put it in use in May, and it's still working on the original set of batteries (December). One sensor goes into the 12v refrigerator, and the other goes into the ice chest on a thin grate placed at the top of the food. The display unit is in the galley. There have been no problems getting a reading from inside the refrigerator, which is all-metal construction. It's nice to know the temps. I recommend it.