Inserts that are configured to be placed in gaps provide between wheel covers and underlying wheel of wheel assemblies. Thus, the locking device can be opened by the mechanical unlocking portion of the key and the electromagnetic unlocking portion of the key, thereby enhancing the versatility of the locking device. When the pressed portion is pressed against the support portion, the support portion is transformed to increase its curvature. The harp also allows for rising half tones in the strings, wherein the pitch of a string is raised by exactly one semitone.