It makes siren noise when touched or senses vibration. This Lock Alarm is a hardened steel padlock which has an in-built alarm Description Feature: Combines locking function with alarming functio procedures, high-tech integrated circuit and digital sensor chip. Can be set to two states: mechanical lock and alarm. Low false alarm rate. Low power consumption. Can be used on door, window, bicycle, container, motor bike, tricycle, pull gate, garden, etc. Corrosion resistant, waterproof and durable to use. Powered by six button batteries. Supplied with three keys, convenient to use. Note:When you place the shackle with groove into lock near key port, then the lock comes into alarming state. When the shackle with groove is placed away from key port, the lock is just in the mechanical lock state. Color: Black Material: Zinc alloy