A product display tray configured for use on a shelf is disclosed. The phosphate anions enable the denture bases, denture liners and tissue conditioners to adsorb cationic antimicrobial molecules. There are two electrodes disposed in the body and selectively electrically contacted with each other. The values for each of the pilot symbols in the set are chosen so as to force the phase reference point to a desired phase state. A compressor structure is provided which can stably introduce a mixture of discharge gas and refrigerating machine oil into the crank chamber without using pressure reducing means such as an aperture and in a manner easy to form a passageway, thereby improving the lubricity of rolling part and slide part in the crank chamber. The housing includes at least two coupling lens mounts on which the coupling lens is fixed on an optical path between the light source and the target, and accommodates multiple light source support members.