I have had the Thermosorks MK4 (4 of them) for 10+years as I used them in my catering business. I kept one in each catering truck. They are not cheap ($75-$80 ea) so when I sold my business they were among some things I kept. The MK4 is also easily calibrated for accuracy.
I also have their SMOKE unit as it has the meat probe and the ambient probe as well as a unit that you can carry around (I wear it around my neck) with the SMOKE unit I also purchased the 12” meat probe for deep frying.
All of these units I purchased directly from Thermosorks
Oh and as mentioned, their customer service is outstanding to say the least