4 IN 1 Door Window Alarm: This door alarm is used to alert you when a door or window is opened by emitting a 125DB alarm or an 80DB prompt. It has 4 working modes, it prevents your children from sneaking out, it can be used as a doorbell for people with dementia patients and it is a perfect wireless home security alarm system for kids safety, burglary, home security, garage,and business security..Mode 1: Delay arm when you leave the house and delay disarm when you back home. This mode is perfect for when you are away from home, if a burglar opens a door or window in your home it will continuously emit a 125DB alarm to scare away the burglar and neighbours will hear the alarm, this can keep your home safe..Mode 2: Alarm when door opens,stop alarm when door close. When you have loved ones or property to protect, when your door, window or cabinet is opened, he can alert you immediately by the alarm sound, so that you can know and react quickly..Mode 3: When a door or window is opened over 15 seconds , it start to emit a "bibibibi" sound to alert you until the door is closed. When a door or window in your home is supposed to be open and needs to be closed, but it is forgotten, this mode will remind you to close the door, preventing you from forgetting and causing unnecessary damage..Mode 4: When a door or window is opened, it will sound a "ding-dong" bell to remind you that someone has opened the door or window. This mode can be used in shops/home/office etc. You will always know when a customer enters your shop/store/office/business, a family member goes out or back home, all under your control, giving you peace of mind..Easy to install: This door alarm comes with double-sided adhesive, you just need to peel off the sticker and install it on the door and door frame, keeping them less than 0.6in apart and on the same plane, and it will work fine..Easy to use: This door alarm system is very easy to use, you just gently press and hold the set button to choose the working mode by the "bibi" sound, after the mode is selected, you just press the touch arm button to get it to work,our manual have detailed instructions to guide you to use our door alarm sensors..Satisfactory After-Sales Service: Amazon Logistics is our partner, we can quickly deliver the package to your home within 1-2 days, we provide a 30-day refund service.If there are quality problems with the sanjie door chimes, please feel free to contact us. So as to give you the best shopping and using experience.