Disclosed herein is a canal type earphone with a pressure equilibrium means, capable of eliminating a pressure difference between a user’s external auditory meatus and an outside during wearing of the canal type earphone. The unit comprises a first hydraulic motor, a second hydraulic motor, cooperating continuous well string gripping chains connected to be driven by the first and second hydraulic motors, a hydraulic power supply connected to provide pressurized fluid to the first and second hydraulic motors and a control system for the hydraulic power supply. The support elements are operated selectively, so as to release, one by one and in succession, the further blister packs aligned and regularly spaced apart, onto the receiving and moving mechanism. The machining is numerically controlled using digitalized geometrical data of the first geometry of the component. A selection section that selects the decurl direction given by the decurl section, and a decurl image that shows a decurl direction on the sheet ejection section for the sheet, are indicated on the selection screen, and the selection section and the decurl image are displayed on the same selection screen. A method for detecting a leak in a piping system is also provided.