A floppy disk control circuit enables a floppy disk apparatus to operate at high speed while current consumption is suppressed to no more than 500 mA, i. The system further includes means for reducing bending moments within the overfilled arch. The elastic polymer material flows into the other of the molding cavities through the connecting flow path, and fills the molding cavities with the elastic polymer material. The net portion 2M is classified in a plan view into a first extending elements Po\u2032 extending in a predetermined first direction #1 and in a second direction #2 that intersects the first direction #1 almost at a right angle and a second extending elements Ps\u2032 extending substantially at 45\xb0 with respect to the first and second directions #1 and #2. The ring members form seats for engaging the formed edges of the lid and bottom.