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Interchangeable Core Systems

SFIC and LFIC provide for quickly changing/re-keying locks by replacing the keyed core.  This task can be performed in seconds by a non-technical person.  The tool used to do this is a key referred to as the control key.  The control key operates and releases a retainer that holds the core inside the lock.  After sliding the cores out, the control key is used to insert the new cores.

SFIC and LFIC systems require another piece of hardware so the cost is increased. The increased cost is offset by the convenience and security of changing a lock quickly and the cost savings of not having to pay for an emergency on-site re-key. The core can then be taken to the locksmith shop to be re-keyed and new keys, made ready for the next emergency change.

Generally, standard keyways do not work with SFIC. There are some key systems that are designed to exist in both SFIC and Conventional keyways. Most commercial keyways are available as LFIC from the manufacturer of that brand of key.  Most commercial manufacturers offer high security and/or restricted keys in both LFIC and SFIC.


SFIC (Small Format Interchangeable Core) is more universal than LFIC.  SFIC cores, and housings, are cross compatible.  However, because of the size of the cylinder the keys used must have a lower profile than most commercial keyways.  Some manufactures offer a restricted keyway in SFIC.


LFIC (Large Format Interchangeable Core) are cylinders made by major manufacturers (Schlage, Corbin Russwin, Sargent, Yale, Medeco, etc).  It is similar to SFIC, but is manufacturer specific. Each manufacturer has it’s own shape of core and they are not cross-compatible. Most manufacturers make many, if not all, of their keys available in the LFIC configuration. They also generally produce a restricted or High Security type of cylinder in LFIC.


We sell, service, and re-key a large variety of small format, and large format, interchangeable core cylinders, and locks.

  • Best/Falcon

  • Medeco

  • Mul-T-Lock

  • Sargent

  • Schlage

  • Yale

  • Corbin Russwin

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