When a Landolt ring optotype is presented in a visual acuity testing unit, an examinee answers a position of a slit of the optotype through an operation of a joystick lever or the like. The hair care appliances include a heating device that is controlled in dependence on temperature by a thermostat adjacent to the heating device. The shielding shell is provided with two shielding shell, attached to an outer periphery of the insulative housing, which their ends are received and retained in the grooves.