ilFornino® Stainless Steel Thermometer 3" Diameter 900°F

I own the Pro Mini oven and live in Florida. Over time, less than 1 year, I noticed that the inside of the thermometer has begun to fade. My assumption is that the high humidity in Florida may be the culprit. However, I feel that the seal between the glass face and the housing is the culprit.
From an accuracy standpoint, this thermometer is on the money. I have used digital thermometers to compare and they both agree.
I have not changed the unit as the original is still very usable, but at a cost of only $ 19.95 with free shipping, I decided to keep a spare. I took a small file and made markings on the outer ring of the old thermometer, just in case the numbers become illegible. That way, I can still detect the proper temperature from the external markings. Perhaps, they should be stamped into the rim as well.