Features: Easily mounted by adhesive tape to window or door. Magnetic sensor switch detects entry, helping protect your home or office. Warning door/window sticker is included in the package. Operates on 2 AAA batteries (not included). Specifications: Open the battery cover, match positive and negative signs, and insert 2 AAA batteries correctly. Close the battery cover. Fix the main unit, which has an on-off switch, at the side of the door or window. Attach the bar magnet to the door frame or window frame with the arrow aligning with the reference line of the main unit. Switch the main unit to the "ON" position to activate the alert state. The device will sound a 90 dB alarm if the magnetic sensor separates from the alarm unit when the door or window is opened. Turn off the switch when not in use. Remove the batteries to prolong product and battery life if the device will not be used for an extended period. Package Includes: 1 x Alarm Unit, 1 x Magnetic Sensor