I had always used zip ties and carried a small nail clipper, sans file, until one flight where my bag came down with the zip tie intact BUT a gash that went all around three edges of the top that was sealed with duct tape and the card inside that my luggage had been "opened" for inspection. When I complained about the destruction I was told that I should not have "locked" it and I would not be reimbursed. The knife that destroyed my 3 trip old suitcase could have easily popped the zip tie, guess that agent was having a bad day.