These are great, cheap and effective. everyone should do this!

Yup, it works like a charm, the retail company i work for has them installed in every store. I've been in the store when they go off, it takes about 15 seconds for the air to be filled with a fog that prevents you from seeing so much as a foot in front of your face. It works very well if the theives don't know their way out thats for sure!