NTC3950 100K Thermistor with Cable for 3D Printer
A thermistor is a resistor whose value varies with temperature. This type of device is rated at 100K ohm.
This particular product is used as replacement 3D printers extruder and heat bed to serve as temperature sensors.
This unit is compatible with most 3D printer makes and comes with the cable pre-attached.
A malfunctioning thermistor can have serious influences on the quality of a 3D print.
The unit is quite easy to replace, simply pull it out and re-tape in the new with some Kapton thermal tape.
In dire cases, some printer firmware allows you to calibrate the temperature PID control system values.