Steelcase CK551

CK551 Control Key
$8.87
Control Key, Removal Key, Pull Key... Different Names, Same Function

The Control Key is required for the removal and installation of lock cores. It does not lock or unlock your lock like a regular key. Most locks must be in the unlocked position to remove the lock core. It is also referred to as a Pull Key, Change Key, Core Removal Tool.
Using a Control Key to Remove and Install Lock Cores