safe pacs?

i've read about 'safe pacs' just yesterday on this forum (regarding robberies) and after looking up safe pacs I'm a little confused. How does this give more security with your items? Wouldn't the thieves still take it with them? They are still a backpack, bag, etc. Do you carry it wherever you go or does it get bolted to some place in the room? Sorry about my ignorance on these but I would like more info before investing in one and having a false sense of security. Whatever information you can give me would surely be appreciated.

I found this on YouTube...I hope this helps.
http://youtu.be/9-wBf-Up1lI

This is the one I use. You put your valubles in it, draw the steel cable tight by wrapping it around the bedframe, headboard, or any other fairly secure object, and lock it. Also a good idea to tuck it out of sight, under a pillow or the matress. It is by no means fool proof, a theif could still find it and break into it with out TOO much effort. But, they would probably not want to spend much time in the room doing so and just move on. There is stainless steel mesh enclosed in the nylon bag.

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

I just got a "20L" pacsafe in the mail today. It seems very sturdy with a steel cable to strap to something solid. I recommend it.

We've been using them for over 5 years, and while nothing will stop a determined thief, they will definitely slow the thief down to the point of making it impractical to continue trying to get into it. I definitely recommend them for peace of mind if nothing else.