The law pretty much mandates that unless you're carrying a firearm, your luggage cannot be secure. Anybody can pick these locks, even without the "master keys"

The law pretty much mandates that unless you're carrying a firearm, your luggage cannot be secure. Anybody can pick these locks, even without the "master keys", and trying for anything else will just get your luggage cut. Anything which needs security needs to travel on your person. So, given that "Secure" is out, I've opted for "obvious when tampered with". I just use boring zip ties that I mark with a sharpie to make them unique (and show if they've been replaced). I'll also toss a handful of unmarked ties onto the "top" of the luggage, so the TSA can zip up when they've had their way with my luggage. I've occasionally sent a piece of luggage through, and found it re-zip-tied with a new tie, with a TSA love note inside.