Magtak Wireless Door Window Magnetic Sensor Alarm is a sleek, durable security device made from high-quality ABS plastic. Powered by 3 LR44 button batteries (included) for long standby time. The sensor triggers an alarm (90-130 decibels) when the unit and strip separate by more than 0.39 inch. It offers 5 adjustable modes to fit different security needs: door-open alarm (stops on close), Ding-Ding doorbell, 30s door-open alarm, "DI-DI-DI" alert, 30s alarm (triggers 15s after door opens), with settings controlled via the side button. Easy to install with tape (included) and supports bidirectional setup with a gap under 0.59 inch. Compact and lightweight, suitable for homes, dorms, and offices. Standard with tamper-proof magnetic sensor alarm. Premium with vibration magnetic sensor alarm is available at an additional charge.