... TheoryTheory is the material layer converts the electrical power into light, illustrating as the following:EL Life Time.Lighting Degree ... lighting, body of car, door decorate, the third bracket light......ect3. Construction And Indoor Aapplication: Building layer label of elivator ... for omnibus, public telephone box , automatic soft drink , road line of omnibus. The Advantage Of EL Poster 1. Extra save ...