The present invention provides a transparent planar body and a transparent touch switch that can improve visibility. Audio sound, based on an audio signal, is emitted within a space comprising an audio beamwidth. The storing, responding, and supplying operations are repeated for subsequent transactions. The present invention also includes novel backstop assemblies that may be adapted for use in shelves of various dimensions. An outer recess is formed to radially face the inner recess and is concave away from a center axis.