I'm skeptical about locks that can be opened with special keys, and prefer to use regular locks or one-time-use plastic ties (the kind that must be cut to open the bag.) I'd just as soon have evidence, even without official note inserted, that bag was opened when it was out of my control. I used to think I was a bit paranoid - but that Australian story has convinced me I was right from the start. Replacement locks are cheap, a jail term isn't.