Interchangeable core (IC) systems let you re-key a door in seconds: turn a special control key, pull the figure-eight-shaped core out of the lock, and snap in a new one. No locksmith visit, no disassembling hardware. For facilities with staff turnover, contractor access, or many doors, IC hardware turns re-keying from a service call into a 10-second task.
SFIC (Small Format Interchangeable Core) is the universal standard: the same figure-eight core size fits SFIC-prepped hardware from virtually every manufacturer (BEST popularized the format). Cores come in 6- or 7-pin versions, and because the format is cross-brand, you can run one key system across mixed hardware. SFIC uses a separate control key that operates a sleeve in the core.
LFIC (Large Format Interchangeable Core) is bigger and manufacturer specific: a Sargent LFIC core fits Sargent housings, Corbin Russwin fits Corbin Russwin, and so on. LFIC cores are closer to conventional cylinder dimensions, which lets manufacturers offer them in a wider range of their own lock functions, and high-security makers like Medeco produce LFIC cores that drop into those housings.
How to choose: if you're standardizing a campus or multi-building facility from scratch, or you want cross-brand flexibility, SFIC is usually the answer. If your buildings are already full of one manufacturer's LFIC-prepped hardware, stay with that LFIC format and simply order cores keyed to your system. Either way, hold the control keys tightly. A control key removes cores, so it is the most powerful key in the system. We stock SFIC and LFIC cores and housings, keyed or uncombinated, and can key new cores into your existing system.
Browse our interchangeable cores, including SFIC and LFIC cores.
Frequently Asked Questions
What is the difference between SFIC and LFIC?
SFIC is a small, cross-brand standard core format; one size fits SFIC hardware from nearly all manufacturers. LFIC is a larger format that is specific to each manufacturer's hardware line.
Can I re-key interchangeable core locks myself?
Yes, that is the point. With the control key you swap cores in seconds. Keep spare cores on hand and rotate them when keys are lost or staff leave.
Do interchangeable cores work with high-security keys?
Yes. Medeco, Mul-T-Lock, and others make SFIC and LFIC cores, so you can combine quick re-keying with patented key control.
What is a control key?
A special key that retracts the core's retaining lug so the core can be removed. It should be held by as few people as possible, because anyone with the control key can swap cores.
Are 6-pin and 7-pin SFIC cores interchangeable?
The cores physically fit the same housings, but 6- and 7-pin systems use different key lengths and cannot share keys. Large facilities typically choose 7-pin for greater master keying capacity.