A flashlight includes a conductive barrel, a lamp unit, a connecting device and a tail cap unit. The armature is pressed against the bearing holder in the axial direction with an elastic member. A second response including the installation date of the measuring circuit is issued from a measurement department in charge of measurement of the transformer. The memory is tested in two stages, using the same BIST algorithm. The screwing element is inserted into the recess via the bottom surface. The stacked resonator includes a first conductor group having a plurality of conductor lines in a stacking arrangement, and a second conductor group having a plurality of other conductor lines in a stacking arrangement so as to be alternately provided opposing to the conductor lines in the first conductor group, thereby establishing an interdigital-coupling together with the first conductor group.