While I agree it is best to place your carry on opposite of where you are sitting that is not alway possible and sometimes you are forced to place it nowhere near where you are sitting. I saw a Lewis N Clark Triple Lockdown Luggage Lock on the Corporate Travel Safety web site and I decided to give them a try. I now use them for both my checked and carry on bags.

The idea of the lock is to make it more difficult for someone to cover their tracks if they use a sharp object to enter your bag because this TSA approved lock prevents the zipper from moving very far. I feel better that my carry on has a lock on it when it is gate checked as well.

I also find this lock handy to secure luggage together (handle to handle) when at the luggage carocell or waiting at a hotel to check in. I use this lock to secure my bag to my chair while eating too.

Shak

http://www.corporatetravelsafety.com...ck-p-1270.html