I ride the train almost everyday and there are some very unsavory characters sometimes. I've had my backpack opened and my phone charger stolen while I was riding on the train one morning and I've discovered my pockets opened several times (assuming a failed attempt). This particular day it was very crowded and I remember the person bumping into me several times. I thought nothing of it at the time since it was so crowded and he seemed to be hitting me when the train slowed down (which made sense). So I've been trying to figure out an idea to give me an audible alert when my backback is unzipped. I think this is the key - I can attach the pull chain to one zipper head and affix the other side to the inside of the backpack. If someone tries to open the chain without pressing the disable button it will fire a relay which will turn on a piezo buzzer letting everyone withing 50 ft know that my backpack was tampered with!

Awesome ! You guys rock on the price for these. Want some of these for basement recessed light fixtures. Even with shipping for a handful of these, it'll probably come out even or better vs local hardware store, and I'll have an excuse to find something else I need from sparkfun.......

AWESOME! I know I could have always bought this at the local home center store, but only when I saw it on sparkfun did I have the vision of an electronic pinata! I can see it now - Each kid pulls the cord once, and if a random number hits a certain value, a magnetic lock turns off, which was holding a flap closed, thereby letting all the candy out!

Now.. to invent the paper mache shield for my arduino...