This is a **Bohan buzzer (security alarm)** that has been used only once. When the button is pressed, a loud sound is emitted, which is useful for crime prevention in an emergency. It's compact and easy to attach to bags and school backpacks, and is recommended for crime prevention during commutes, school trips, and walking at night. Operation has been confirmed. Please purchase only if you understand that this is a used item. Instant purchase is OK ☺️