Fortress locks have over 200,000 different lock combinations. The standard CLIN can be operated by a standard key (CLK-SUS) that can fit on any CLIN, CLIS and CLSS type lock. For ease of use all Fortress locks provide key insertion in two directions.

Each different key combination is allocated with an engraved code onto the lock and key, of up to maximum 30 characters (3 lines of 10 characters), this engraving code is used to identify locks and keys and is recorded in a database for continuous cross reference. Required engravings are therefore to be provided with each order.