A fixed inductor is a type of passive electrical component that stores energy within a magnetic field when exposed to electric current. Unlike a variable inductor, the inductance of a fixed inductor cannot be adjusted. The inductance of a fixed inductor is fixed in design; however, the magnetic characteristics of the inductor may vary within a narrow range. Fixed inductors come in many different sizes and shapes, ranging from large coils to small surface-mount devices (SMD). The properties of a fixed inductor depend on the core material, construction, and shape of the coil. Common applications of fixed inductors include filters, oscillators, and power supplies.