Wide application: these door entry alarms are suitable for various kinds of doors and windows with handles, applied in families, rental rooms, dormitories, hotels, shops, warehouses and other places of anti-theft, also an effective helper for traveling to protect the safety of you and your family | Easy to use: just insert 3 batteries (not included) into the alarm for door handle, turn on the side switch, and hang the alarm on the inside of the door handle, then you can enjoy a secure living place | Working principle: hang up the triggered home security alarm, and after the red light flashes for about 30 seconds and stops, the door alarm officially enters the alarm state; When someone touches the door handle or opens the door or window and generates vibration, the alarm will immediately sound an alarm to remind you | Dual-mode alarm: the switch and alarm mode is in an integrated key, pushing up is the doorbell, pushing down is the alarm sound; When the doorknob sensing alarm is not in use, the switch key can be restored; Besides, the alarm sound is up to 120 dB, no omissions, no false alarms | Adjustable sensitivity: there are 3 levels of sensitivity to be adjusted, which can be set according to your needs; Generally we recommend you to set it to mid-range, which can effectively protect your home and let you rest assured