The Vaillant thermistor works by decreasing current resistance in a manner that is inversely proportional to the temperature of the thermistor. The printed control board (PCB) sends a current to the thermistor and can tell whether more or less heat is needed by the resistance.
Comes with attached clip
Technical specification
Waist Sizeab15cd94gxTypeThermistorSupplier Part Number101771Brand NameVaillant