Product Description Number Display Wireless Door Sensor Your Best Choice for Family There are the default when you open the package.   Each door sensor is paired already before delivery, you can use them directly! The default tone is “Ding-Dong”. The default serial numbers of four door sensor is 1/2/3/4. We've paired the four door magnets with the two receivers, and no matter which number of door magnets sends the signal, the two receivers will ring together. If you set the devices in house/store, you can set one receiver in first floor and another one in higher floor. When someone coming, you never miss them!   (If you set the receiver on the first floor and turn it up to full volume, you can hear it on the second floor too! So, the second receiver you can set at a higher floor!) 5 Level Adjustable Volume/300m Long Wireless Distance When there are elderly people with dementia or hearing impairment at home, the door sensor will sound an alarm to remind you If a thief or bad guy tries to sneak into your home, the door sensor will make the loudest noise to scare the bad guy away When your child tries to open the door and window and wants to go out, you can find out in time Immediately alerts you when pets in the house slip away How to clear the all setting of receiver? Long press the bottom button until the screen lights up and make sounds. How to change ringtone? Short press the previous/next button to choose your favorite music. Long press the Volume button for 5s, until light flashes and make a “Ding”sound. Make door magnet separate quickly, and the receiver will sends a pairing signal, "Ding". The setting is successful. Make door magnet separate again，confirm whether the ringtone is your set.If YES，the pairing is successful. How to pair one-on-one Power up this receiver (the other receiver is unplugged). Clear the setting of the receiver.(long press the bottom button) Long press the Volume button, until the receiver make "Ding" and the digital lights up Make door magnet separate quickly, and the receiver will sends a pairing signal, "Ding". The setting is successful.Make door magnet separate again，confirm whether the number is your set. If YES，the pairing is successful. Correct installation of door magnets