This is a review of an inexpensive MH-1210 Chinese bang-bang thermostat that was purchased on eBay for around A$13 complete with thermistor sensor and postage.
This one was a replacement for one incorrectly sent (wrong supply voltage).
Above is the thermostat.
The label clearly states this is calibrated for an NTC 10k B=3435 thermistor.
Above, a view of the interior.
The documentation does not provide any relevant information on the power source and polarity is not indicated on the terminal labels (in English), but tracing the circuit shows that the two power terminals connect to the AC terminals of a bridge rectifier, to the input is not polarity sensitive, in fact it should be possible to run it from low voltage AC.
Test
Experience advised that calibration be checked. A check of the thermostat was made with 10k and 1k0 0.1% resistors in place of the thermostat, and calibration constants calculated (Two point thermistor calibration).
This one is close to the specification of 10k/3435.