This classification handles specialized and highly specialized electronic components that are not classified into major electronic component categories. It includes electronic components specialized for specific functions or applications such as crystal oscillators, thermistors, varistors, photocouplers, reed relays, piezoelectric elements, magnetic sensors, optical elements, high-frequency components, and EMI countermeasure components. It deals with specialized electronic components used in control circuits for manufacturing equipment, measuring instruments, communication equipment, and sensor circuits.