Below is a list of EMI Shields manufacturers from Mission Viejo, California. EMI shields are materials or products used to redirect or absorb electromagnetic interference in order to protect sensitive electrical devices. Electromagnetic interference, or EMI, refers to the magnetic field which is created by electrical currents. EMI can travel through wires, electrical circuits and conductors, and is created, to various degrees, by everything that can conduct electrical energy; examples of which include electrical wires, electrical appliances, computers and all electronic equipment.