What do the different key options mean?

infographic of keyed-different keying option KEYED-DIFFERENT:

Each lock is opened by its own unique key that does not open any other lock in the set.  You receive two keys per kit ordered.   When ordering additional kits, you may not have them keyed to any previous number received.

infographic of keyed alike keying option KEYED-ALIKE:

This option provides "same key" convenience and eliminates the need for multiple keys where numerous locks are used.  All locks in the set are opened by the same key.

Most Universities and Companies will key desktop kits alike within a department.  This aids in key control, as the administrator often retains the keys as one set can open every lock, and the user doesn't need this access.  You receive two keys per kit ordered.  When ordering additional kits, you may order them keyed to the same number, if applicable.

infographic of Master-Keyed keying option MASTER-KEYED: (possible additional charge per lock): 

In a Master Keyed System, a master key opens all the locks in the system although each lock also has its own unique key.  This allows an authorized person to have supervisory or emergency access to each lock.

When ordering additional kits, you can have them keyed to the same master key number. You will receive one Master Key at no charge with your first order. Additional Master keys can be ordered, however, we do suggest limiting the number of people having complete access to your computer systems.