We have a number of padlocks that use a key to enable the resetting of the combination. This is ideal when you do not want users to be able to reset the code but you still need to have the ability to alter the combination when required. We find sites catering to groups of visitors find this a very useful feature.
The Shield C50 brass combination padlock is an ideal outdoor heavy-duty product. The four-digit code can only be changed using the reset key so you can give the code to the current group and then change it for the next one. As the key holder, you are safe in the knowledge that the group members cannot alter the code whilst using the padlock.
If you are located near the coast then you may wish to consider using the Abus 180IB/50 weatherproof combination padlock. This is a padlock specifically designed to withstand the salty environments found in coastal locations. It comes with a stainless steel shackle and non-corrosive internal components to give it that extra protection. The code can only be changed using a reset key in the same manner as the Shield C50.
Both padlocks come in the standard shackle length or for those times when a bit more room is needed, then you could use the long shackle versions.