Package:3 x Door Stop Alarm: This is an upgrade door stop than others.It is more durable than others with better quality. 3 Sensitivity Levels - Low - Medium - High, with an adjustable sensitivity switch on the side. Very loud shrill that would definitely scare someone away with 120db alarm. Each Weight: 128g You can use it as common door stopper when turn down the ON/OFF switch,hold door in open position. No installation required.Each requires one 9vbattery(Not include).Portable and easy way to add peace of mind when traveling or working alone. li> They might pick your lock but they cannot get inside your hotel room, apartment, or home when secured by the Super Stop Alarm. With box package which protect the product well Battery Installation: Make sure the on/off switch is in the "off" position. Turn the unit upside down and open the battery compartment Install one 9-volt battery (not included) and close the compartment. The on/off switch will prevent the unit from accidentally sounding. Requires one 9 volt battery - not included Note: The gap between door bottom and floor should be 1 - 3.5cm