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Cores
Interchangeable cores let you rekey a lock in seconds with a control key, which is why facility managers, schools and locksmiths use them. Browse SFIC cores such as the BEST 1C6 and 1C7, uncombinated and construction cores from Falcon, LFIC cores from Accentra (Yale) and Sargent, and the Schlage FSIC core. Browse the full cylinders, cores and key blanks range.
What is an interchangeable core?
An interchangeable core (IC) is a removable lock cylinder that lifts out of its housing with a control key, so a lock can be rekeyed or swapped in seconds without taking the lock apart. The core holds the pins and the keyway, and the housing stays in the door. That is why interchangeable core cylinders are the standard on schools, hospitals, property portfolios and any building with many openings: a lost key means swapping one core per door, not replacing hardware. Our SFIC vs LFIC buying guide adds more detail.
Identify your core format before you order
Check the lock or housing you already have before buying cores: SFIC, LFIC and FSIC are not interchangeable with each other. For a full SFIC vs LFIC comparison, see our SFIC vs LFIC guide.
SFIC is the small format core, LFIC is the large format core and FSIC is the full size core, and they do not interchange. The SFIC (small format interchangeable core) follows the Best IC standard and is shared by many manufacturers. LFIC (large format interchangeable core) is the older, larger style, used by brands such as Accentra (Yale), Sargent and Corbin Russwin, and each maker has its own. FSIC (full size interchangeable core) is the Schlage full-size core. Compare the core with the housing: if it will not enter, it is the wrong format.
6-pin vs 7-pin cores
A 7-pin core gives more key combinations than a 6-pin core, and is chosen when a facility needs a larger master key system. A 6-pin core suits smaller systems and most standard facilities. The catalog lists both: the BEST 1C6 and 1C7, Falcon C646 and C647, Arrow 100CRP and 7100CRP, Accentra (Yale) 1210 (6-pin) and 1220 (7-pin). The pin count must match the housing, the key blank and the keying system, so confirm it before you buy.
Uncombinated, construction and keyed cores
An uncombinated core has no pins fitted and is pinned to a key code later, while a combinated core is delivered pinned and keyed. Construction cores let trades use the doors during a build with a temporary key: the Falcon C606CCA (6-pin) and C607CCA (7-pin) are black construction cores with an "A" keyway, and the Corbin Russwin 8000-CT6 is a 6-pin construction core. Keyed cores, such as the Kaba Ilco 28026 and 28027 or the Accentra (Yale) 1210 KD, arrive combinated for immediate use. Many locksmiths stock uncombinated cores and pin them to the system keying.
Control keys, rekeying and master keying with interchangeable cores
A control key removes the core, while an operating key opens the lock. To rekey a door, insert the control key, turn it to release the core, pull the core out and drop in a new core keyed to the new key. The old core is rekeyed or retired offline. Master key systems are built on top of this, with change keys, master keys and a control key per system. Read the master key systems guide before ordering a system, and see core swap, rekey or keyless for the options at shutdown.
Brand compatibility: what fits what
A core fits a housing only if the format and the keyway system both match. SFIC cores from different makers fit the same Best-format housing, such as the Falcon CB846, which is uncombinated with Best style capping. A BEST housing can take a Falcon, Arrow, KSP or Ilco SFIC core, but the keyway and the control key system must also match, or the lock will not be part of the same master key system. LFIC cores are proprietary: a Sargent 6300 core will not fit a Yale or Corbin Russwin housing. Our IC housing guide covers the housings.
Interchangeable core brands and series in the catalog
| Brand and series | Format | Pins | Notes |
|---|---|---|---|
| BEST 1C6, 1C7 | SFIC | 6 and 7 | Standard SFIC cores |
| Falcon C646 to C649, CB846, CB847 | SFIC | 6 and 7 | Uncombinated; Best style capping on CB models |
| Falcon C606CCA, C607CCA | SFIC | 6 and 7 | Construction cores |
| Arrow 100CRP-UCX, 7100CRP-UCX | SFIC | 6 and 7 | Uncombinated, plain face |
| KSP 206 series | SFIC | 6 | Satin chrome and satin brass |
| Kaba Ilco 28026, 28027 | SFIC | 6 and 7 | Combinated, keyed different |
| Accentra (Yale) 1210, 1220 | LFIC | 6 and 7 | 0-bitted, keyed different and keyed alike |
| Sargent 6300, 65-6300 | LFIC | 6 | Removable core; unassembled version |
| Corbin Russwin 8000, 8000-7, 8000-CT6 | Corbin Russwin IC (check listing) | 6 and 7 | 6-pin construction core |
| Schlage 23-030 | FSIC | See listing | Full size core, C keyway option |
Most requested interchangeable cores
The interchangeable cores our customers look up most often right now:
- Sargent 6300 6-pin Large Format Interchangeable (Removable) Core
- BEST 1C6 6-Pin Standard SFIC Core
- Corbin Russwin 8000-7 Interchangeable Core
- Schlage 23-030 FSIC Full Size Interchangeable (Removable) Core
- Corbin Russwin 8000-CT6 6-Pin Interchangeable Core
- BEST 1C7 7-Pin Standard SFIC Core
Related categories: mortise cylinders, mortise locks and cylindrical lever locks.
What to have ready when ordering interchangeable cores
- Core format: SFIC, LFIC or FSIC, and the lock or housing brand.
- Pin count (6 or 7) and keyway or key system.
- Uncombinated, construction or combinated and keyed.
- Control key, change key and master key requirements for the system.
- Finish (for example satin chrome 26D) and the quantity.
Cores need the right keyways and blanks: cylinder keyways and keying compatibility lists the key profiles.
Ordering quantities or a combinated set? Request a quote for volume pricing. Schools and agencies can submit a government or school PO. Orders placed before 3:00 p.m. ET on business days ship the same day after card approval, and ground shipping is free on orders of $450+. Need help matching a core? Call 718-814-6300.
The tables and selection notes on this page are compiled by National Lock Supply from manufacturer catalogs, templates and product listings. Last reviewed: October 2026.
Frequently Asked Questions
When should I choose a 7-pin core over a 6-pin core?
Choose a 7-pin core when you need more key combinations, such as large master key systems with many levels. A 6-pin core suits smaller systems and most standard facilities. The pin count has to match the housing, the key blank and the keying system, so check it before ordering.
How does rekeying work with an interchangeable core?
Insert the control key, turn it to release the core, pull it out and install a core keyed to the new key. The lock stays on the door, so a rekey takes seconds with no tools. The removed core can be rekeyed later at a bench by a locksmith.
What is an uncombinated or construction core?
An uncombinated core has no pins fitted and is pinned to a key code later. A construction core is a temporary core, often with a black face and a construction key, that is replaced by the permanent core at turnover. Examples include the Falcon C606CCA and C607CCA.
Are SFIC cores from different brands truly interchangeable?
Physically yes, since SFIC cores follow the same standard and fit the same housing, such as a BEST housing. The keyway and the control key system must also match for the core to work with a key system. Check the keyway name before mixing makers.
What is an FSIC core, and how does it differ from SFIC?
FSIC is the full size interchangeable core, a larger core used by Schlage, such as the Schlage 23-030. SFIC is the small format core that follows the Best standard. They are different sizes and do not interchange, so the core must match the housing format.
What is the difference between a core and a cylinder?
A cylinder is the complete keyed unit. A core is the removable part of a cylinder system that holds the pins and keyway, and it sits in a housing. An interchangeable core cylinder is the housing plus the core. The core can be swapped without disturbing the lock.
What is a control key?
A control key is the special key that removes an interchangeable core from its housing. It is different from the operating key that opens the lock. Control keys are tied to a keying system, so keep them with the facility manager or locksmith, and track them like master keys.
Can I use an LFIC core in an SFIC housing?
No. LFIC and SFIC cores are different sizes and do not interchange, and LFIC cores are proprietary to each brand. Identify the lock or housing format first, then order a core of the same format, the same pin count and the same keyway, so it fits and works with your keys.