The door alarm is small enough to fit on any door or window and comes with two AAA batteries, each of which lasts two years without frequent battery replacement. This door chime for business can be used as a doorbell for your retail shop for your commercial to remind you when someone walks into your store, you will never miss any customers(visitors). 4 Working Modes:1--Instant Alarm(it alarms when door opens,it stops alarm when door closed)2--Entry alert(Just one welcome ring ding-dong 3--Door closing reminder(the sensor emits "dididi"sound every 10 seconds until door is closed)4--Instrude alarm mode (Alarm will last for 1 minute if your door is being open). ?door alarm with remote?The distance between the alarm and the remote control is 82FT, and you can control your alarm on or off from the second or third floor. ?0-120 dB Adjustable?Door window alarm up to 120 dB loud sound can run through the whole building and even to your neighbor's house, easily scare off intruders. [Easy to Install] The door alarm sensor is paired before it reaches you, and you can simply install the door alarms for home on the door and window to turn on the switch and start working, no wiring or electrician installation required. Magnetically triggered - Alarm sounds when window or interior door is opened by kids elder & burglar ,Prevent any mishap.(comes with a 90-day free return and a 365-day exchange service).