A patient transfer device has four casters and two counter-rotating steering wheels. The polarization conversion system includes an incidence plane through which light emitted from the light source enters, and transmits a beam with a first polarization from the light entering through the incidence plane and reflects a beam with a second polarization toward the incidence plane and then changes the polarization of the reflected beam. The composition can be used to make a variety of components such as flooring, gaskets, stair treads, weather stripping, hinges, sound absorption components, trim, seals, grips, surface treatment for various surfaces, bumpers, toys, buttons, and tubing. Before the customer purchases a commodity, a sales assistant can effectively identify the customer and the commodity shelf or commodity of interest and promote the sale of the commodity. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.