Apparatus and methods directed to a hand holdable flashlight including a battery housing having an undercut groove to which is removably fitted a head of an interface device which itself is removably securable to the object. The sex aid includes a surface portion intended to contact the external or internal surfaces of users or a user; and one or more hole at the surface portion in fluid contact with the connecting mechanism. The optical energy emerging from the medium and entering the detector originates from the source is scattered by the medium. A non-conducting spacer is on the substrate and electrically isolates a gate electrode from the substrate. This will dramatically improve the trigger-based efficiency. Concerning the depressing operation on the melody key range 102, CPU 21 specifies a jins or a predetermined temperament from maqam data or temperament-type data based on depressed keys in an accompaniment key range 101 of the keyboard.