Medeco High Security Locks of Salem, Virginia, has launched the KeyMark X4, a next-generation lock with exceptional retrofit capability. The locks have up to four times the masterkey capability of standard small format interchangeable core (SFIC) systems. In most cases, facilities with SFIC systems do not need to change hardware to accept the new locking cores. In addition, users are assured of protection against the unauthorized duplication of keys. Key blanks are available with a conventional key bow that is custom coined for security or as Hybrid Prox or iCLASS electronic key blanks. The Hybrid key combines a snap-on plastic head containing a 125 kHz Prox or 13.56 MHz iCLASS RFID credential with a nickel-silver key blade. The dual function credential can interface with an electronic access control system and also operate the mechanical cylinders.