An optical element includes a base material, a liquid-repellent member provided on at least a part of a surface of the base material, and a light-reducing member provided between the base material and the liquid-repellent member to protect the liquid-repellent member from radiation of light by reducing the light. Once fastened, the plurality of curved panels may be lined with a liner and used for fluid storage. If the supplied information signal is found to be moving picture information, the CPU detects free blocks each made up of a plurality of clusters by referencing the FAT information of a hard disk and records the moving picture information in unit of detected free blocks. A delay timer, coupled between the first and second timers, pseudo-randomly delays initiation of the second timer from the start of the first time interval. For example, the user may be permitted to select a particular payment card number and real destination address as previously provided to the intermediary.