high-frequency transformers and inductors.they are enameled wire wrapped, with iron or magnetic cores inside.transformer is mainly used for voltage transformation, its basis is the law of electromagnetic induction.
Inductor Choke Coils are made of wires wound around an insulating tube one by one. The wires are insulated from each other. The insulating tube can be hollow, or it can contain iron cores or magnetic powder cores, referred to as inductors. Expressed by L, the units are Henry (H), Milli Henry (mH), Micro Henry (uH), 1H=10^3mH=10^6uH.
In radio communications, broadcast television, and automatic control, it is used as a component of voltage amplification, power output and other circuits.