This is a through-hole, electronic part with a RoHS compliant rating, manufactured by Tyohm. The WMF21-3D15MPUP8CB3.5 has a NTC Thermistor, which is a temperature-sensitive device made up of a negative temperature coefficient of resistance. This thermistor is commonly used for temperature sensing, and the WMF21-3D15MPUP8CB3.5 is a three-pole device designed to measure and control temperature in a variety of applications, such as HVAC systems, water and gas flow meters, and chemical and food processing systems. The thermistor also has a maximum operating temperature of 150°C and a resistance of 3.5 ohms at 25°C.