A system configuration device provides system configuration information to a system unit. A first pattern comprises an image at a first image size and a character string at a first character string size. The MM may include advertising information. The elastic component enabling a course fitting of the interface to the patient and the inelastic component enabling a final fitting of the interface to the patient. In such constructed battery pack, an ejected gas, at the operation of the safety vent of the battery pack, is externally released through an interface between the resin and metal.