I don't have MLT or HLT thermometers, I use a Thermapen for that. My boil kettle (and for large batches HLT) has a weldless Blichmann Brewmometer. I use it for monitoring ramp to boiling, and for monitoring chilling. And when I do use it as HLT, I'll use it for rough approximation of mash/sparge water temps, and use the Thermapen to confirm.