Triggering the alarm is easy to do.  The package comes with two ways to trigger siren.  One is a pin you pull out and the other is an accessory that is a tweezer-like device and supposed to be used on doors or windows. 

I use the tweezer-like device to trigger the siren.  When the prongs of the device are held together the alarm is silent.   There's a pic of the device on the previous pages.  Release the prongs and they spring open, sounding the alarm.  (This is why the device works great when placed between a closed door or window, if the door is opened the prongs spring open and the alarm is sounded.)  Now, you can either pull the pin or just let the prongs open.   It's great!!  You keep the flat prongs between your thumb and forefinger when grasping the bars.  Lift your hand a little and the 130 db siren is sounded.   Using the prongs may produce a different sound. 

The other way is to use the pull pin.  The siren comes with instructions that show how to use the pull pin so a flick of the wrist is all it takes to trigger siren.