I'm with RedneckWelder. I use a simple 5" stem 1" dial analog vintage stainless steel USA made stem thermometer with a pocket clip sleeve. Mine is over 40 years old and it still reacts fast to temp changes and shows a reading within 1 degree of my very accurate liquid in glass thermometers when compared. There are a couple new ones out there for about $10-12 or so that have +/-1% accuracy. I think Thermco makes one. Look on the Zoro website, they had a couple 1% stem thermometers available last time I checked. Newer stem thermometers are usually China made though. If you get one from a known manufacturer with an accuracy spec they are still quite good, but most of the cheaper ones out there are only +/- 4% of full range accuracy at best. That's pretty terrible. My thermometer goes from +20 degrees to +125 degrees F. That's the best range I have found for doing automotive AC output testing, because the range is small enough that every tick on the dial represents one degree instead of two or more.