This video clip shows how the zip can be breached with an ordinary ball-point pen in a second, and resealed without leaving any trace!
However, in order to reseal, one has to move the zipper over the opening thus giving us some possible solutions to detect tampering. (I have no commercial interest in the following products or companies):
- use a zip tie to lock the zippers against the baggage handle. In fact, with a zip tie, you can probably do away with the padlock. [friend’s suggestion]
- use a Tell-Tag