A flexible-piece-receiving hole is opened in the bottom wall while ensuring an adequate contact force is obtained between the leaf spring and a male terminal and preventing the leaf spring from excessive deformation, and in turn, the workability of operation of disengaging the flexible piece from the female terminal is enhanced. The application interface can also be displayed on a second display that is integrated in the dual-display mobile device. The ligaments may further include first and second end-to-end attached sections, between which are configured angled and opposingaligning incisions.