Applicable to multiple scenarios -- Easily mounted by adhesive. Type to window or door. Ideal entry warning for homes,apartments,offices,hotel rooms,garages,and more！ Easy to use -- Magnetic switch detects your door or window.Easy stick installation and operation, press on/off switch to power on/off then insert 2 PCS AAA battery (battery do not contain in the box),tear the double-sided adhesive on the backpack, paste the door knob alarm on your target position. Super loud 90 dB alarm -- When someone opens the door or window illegally (the relative position of the primary and secondary parts changes), the alarm can issue a strong alarm, warning the intruder to leave and remind the owner. prevent kids and babies going out the house, protecting your home or office whether you are in or out. High quality -- Super suitability and stability. 100% New and high quality Package include -- 15 packs super loud, suitable, stable, dustproof window door alarms