Cylinders - KeyRETRO KeyRETRO is a backwards compatible design with UNION's traditional masterkey platform, offering enhanced security to existing masterkey suites with a patent on key and cylinder assembly until 2028, providing peace of mind that keys cannot be copied. JM1 - Rim CylinderSingle rim keyed cylinder For use with nightlatches or ot… JM2 - Mortice Screw-in CylinderSingle screw in keyed cylinder For use with special narro… Downloads Master Key - keyRETRO (.pdf, 483 kB)