Seems like a ghetto-way to get temperature control. I'm sure the hysteresis, etc with this thing is ridiculously bad. However, I'm sure it would beat manual adjustment of a Variac.
It looks like the max temp on that is 150, which is too low for an HLT, and would be really limited for a MT. I think there is a quite a few options out there for temp control, however price does go up with ease of use / accuracy.
