A plunger and a piston are displaceably held in a housing for opening and closing a valve path defined in the housing, and a single common seat block provided for the plunger and the piston is fixed to the housing and has seat portions each formed from a soft material for respective of the plunger and the piston to be pressed thereon. When no graphics processing activity is detected for a period of time, then a timing controller for a display device is instructed to capture a current image and repeatedly display the captured image. A handle is disposed at the proximal end of the inner catheter, and an enlarged tip is disposed at the distal end thereof. A circular, transparent advertising cover is mounted on a lower panel. The end part of the exhaust pipe includes two scalloped shapes that each correspond to a preferred acoustic radiation direction, separated by advanced parts that can limit the acoustic radiation, whereby the scalloped shapes are offset upward relative to the horizontal median plane.