Product review (3 stars): Batteries installed wrong, one dead.
This unit runs off two LR 44 cells in parallel. One of them was installed upside down which shorted the other. So one cell is at 1.5v and the other at 0. I threw out the 0v cell and am running it off 1 cell. The batteries themselves look super cheap and one was slightly rusted.

There is no "user" way to change from C to F but some have posted hacks. The unit is intended to be panel mounted. There is also no on/off switch so the unit is intended to always display temperature for the life of the batteries (battery in my case).

I'm using it to monitor the print chamber temperature on my 3D printer and it works great for that.