I use 6 of the Iris open/close sensors inside 3 frig/freezers in my home. My frigs average in the low 30’s, and 2 freezers are at -2F, the other is at -21F.
These have been very reliable, and the device handler allows for a temperature offset (if needed). All 6 are inside the frig/freezer, and I get the benefit of knowing open/close state and temperature. I bought these as soon as these hit the shelves at my local Lowes, so somewhere around Aug/Sept 2015. These are frequently used, and my battery levels are averaging 55%. Pretty darn good bang for the buck if you ask me.