A gear includes a metal core and a synthetic resin tooth body. The sheaths include a side-port opening through which a gliding catheter may be deployed during diagnosis or treatment of tissue. In case of circumferential rib, the rib is provided with the curved surface comprising a plurality of the convex curves and a plurality of convex curves alternating therewith so that the curved surface is waved in the tire circumferential direction. The memory device also includes a redundant memory cell array, a redundant decoder and a redundant switch circuit. The sound-generating portion and the mounting portion are of different materials.