"Personal Alarm System: Volumetric alarm"
Personal alarm system
A volumetric alarm is a smart way to protect yourself and your
loved ones.
Instead of electronics, this type of alarm system relies on a change
in air pressure to warn you of any danger.
As soon as a door or window is opened, a 105 decibel alarm sounds...
loud enough to warn you and scare off the criminal. This alarm is
portable and perfect while traveling.
Personal warning system:

Keep-I volumetric alarm
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You don't need any installation or wiring, so it's
an easy system to use.
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Gives protection of up to 1000 square feet within
a closed space.
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This alarm system is so sensitive that you can
even set it to go off when someone touches a door handle... pretty
slick.