Waseda-style Quiz Buzzer Miniature Collection ・Correct/Incorrect Judge Unit ・Buzzer Button (Red) This is a set. It was displayed indoors, away from direct sunlight. All buttons function correctly. Each button has only been pressed a few times, so I believe the batteries still have plenty of life left. Please consider purchasing only if you understand that this item has been owned by someone else. Instant purchase is welcome. If you have any questions, please feel free to ask.