This style of locking system is basic yet very effective.  We install a brass grommet just under the edge of the zipper chain on the end of the bag that closes.  When the bag is zipped close you place a padlock through this grommet and the shackle of the padlock goes over the top edge of the zipper chain.  Because of the unique placement on the grommet the shackle is just behind the slider body and DOES NOT allow the zipper to be opened by blocking/stopping the slider from moving backwards.

The type of locking system on this bag has advantages of bags that have the lock incorporated as a part of the zipper. In the event you need to change the lock, which can arise from things like personnel change or lost keys, you can just switch or replace the lock instead of discarding the bag or sending it out to be re-keyed.  This bag is less costly than bags that have the locking mechanism as part of the zipper.

This bag also allows you to place any type of plastic or wire safety seal/strap through the loop, which would also prevent the bag from being opened if that is what you prefer to use instead of a padlock.  That is also another definite advantage over bags that have the lock mechanism right on or at the end of the zipper.

You can purchase your own padlock, which give you options in the security level by the quality of the lock itself.  This grommet locking system can be implemented on almost on the zipper bags we produce. 

While no bag is theft or pilfer proof, being able to lock the bag is certainly a deterrent and helps keep the honest people honest.