FR103 is a thermistor component. It is a type of temperature-sensitive resistor composed of a ceramic material, typically a mixture of metal oxides such as manganese, nickel, cobalt, iron, and copper. This component has a negative temperature coefficient, meaning the greater the temperature, the greater its resistance. It is used in a variety of electronic devices to measure temperature, control power circuits, and HVAC systems, and as an over-temperature protection feature. The resistance of the FR103 thermistor decreases as the temperature increases. It has a wide operating temperature range of -55 to +150°C and it is available in a variety of sizes.