I think they are like miniature watch glass things that
keep the sample clean.
I also acquired a device which, using a heat sensor device,
will maintain +- .01 C, which I find a fucking amazing.
It's output control is only 150 watts, for a thermoelctric Peltier junction device,
but it should handle this resistance heater device as well.
I'm not sure,
but the temperatre sensors are small enuff that i can run the Hg thermometer AND the sensor in paralell and cross check..