Funey Upgraded Door Stop Alarm for Home, Pack of 3 Package:3 x Alarm Door Stop: 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. 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. Requires one 9 volt battery(Not include).Portable and easy way to add peace of mind when traveling or working alone.