Sometimes security measures must be put in place. You are able to achieve this by locking your cabinets.

Starting with the master key, you can lock/unlock your cabinets with this. When locked, other players are unable to insert/extract or even open or close your filing cabinets.

If your filing cabinets are locked but you want certain players be able to access them still, you can give them a key copy. Rightclicking a locked cabinet that you own with this will create a key copy in your name. As long as other players have your key copy in their inventory, they are able to access the contents of your filing cabinet. They cannot lock/unlock cabinets with a key copy - only the Master key can do that.