Where many users need to be able to open a particular padlock, a 'Combination Padlock' provides a practical alternative to a 'Key Operated Lock' which would require keys to be issued to each of the potential users.
A 4 tumbler combination offers a higher level of security than a 3 tumbler unit, but whichever type you choose, make sure that the combination code can be reset or changed quickly and easily by the user and as often as required.
Changing the combination when you believe that the code has been compromised, or you wish to prevent one of the previous users from continuing to open the padlock maintains the integrity of your security.