By Kent · Lock Depot Staff Writer

Three product names, one core format

Medeco sells its large format interchangeable core under three product names: Biaxial, Medeco3 and KeyMark. Each comes in its own keyway, in five or six pins, in several finishes and in different states of keying. On a quote they read like alphabet soup: 320201-26-00P, 320201W-26-G3S, 310100K-26-8ES. This guide sorts out what the listings tell us, and, just as important, which questions only your existing system can answer.

What all of them share, per the listings: the figure-8 large format core, ANSI/BHMA Grade 1, a 2 year limited warranty, and a pull-with-the-control-key swap. You pull the existing core with a control key, slide the new one in, and the lock never leaves the door. The listings say Medeco LFIC cores come for Schlage, Corbin Russwin, Sargent and Yale housing formats, so verify your housing before ordering.

The three platforms

Platform	Keyway in these listings	What the listing says	Example
Biaxial	00	The original high-security platform; direct replacement for an existing Biaxial system	320201-26-00P
Medeco3	G3 or DL	UL 437 listed; pick, drill and bump resistant; M3 sidebar	320201W-26-G3S
KeyMark	8E	Restricted keyway program; keys are factory-controlled	310100K-26-8ES

Biaxial 00: matching an existing system

Biaxial is the platform that made Medeco's name, and the listing says it uses the classic rotating pin technology. The reason to buy a Biaxial core in 2026 is simple: you already have a Biaxial system, and the core you are replacing is in the 00 keyway. This is a replacement part, not a design choice. The listing says these cores are direct replacements for an existing Biaxial system, and that if you upgrade to Medeco3 later, the housing is the same and only the core changes.

It comes in more than one keying state. The 320201-26-00P ships combinated, which the listing defines as pinned, with two operating keys and one control key. The 320201-26-00S is sub-assembled: pins included, not set, no keys. The 00 keyway also shows up in satin chrome, bright brass and oil rubbed bronze.

Medeco3: the one specified for UL 437

If a door spec says "high security" or calls out UL 437, Medeco3 is what the architect means, according to the listing. It describes Medeco3 cores as UL 437 listed, with pick, drill and bump resistance, and says the M3 sidebar adds a layer that a standard pin tumbler lock does not have. These listings come in two keyways, G3 and DL. The G3 appears on the 320201W numbers and the DL on the 320201T and 320201J numbers, and the listing for the DL keying also appears on a 5-pin core, the 320101T-05-DLN.

I will not decode the letter after the series number. The listings do not say what W, T, J or K stand for, and guessing would be inventing a spec. What I can say is that the keyway name in the title (G3, DL) is the one to match against your system.

KeyMark: when copies must be controlled

KeyMark is Medeco's restricted keyway program in the large format. The listing says keys are factory-controlled, so nobody walks to a hardware store and copies one. The 8E keyway shows up on the 310100K-26-8ES, and on the 322201K numbers, such as the 322201K-26-8ES. The listing for the 8E core also pitches it as an upgrade for a building already running LFIC housings. For the small format version of the same family, read the KeyMark X4 SFIC core guide.

5-pin or 6-pin

The pin count is in the title, so read it. Most of these cores are 6-pin. The 5-pin Medeco3 cores in the DL keyway (the 320101 series) are a separate series number, and the two do not mix inside one keying system. Order the pin count your system uses. If you do not know it, pull a core and count the pin chambers, or send us a photo of a key.

Combinated, sub-assembled or uncombinated: read the body, not just the title

This is where orders go wrong. The listings use three words for keying state:

• Combinated: pinned to a key change, with two operating keys and one control key. Example: 320201-26-00P. The 320201T-26-DLT is also titled combinated.
• Sub-assembled: pins included but not set, no keys. Your locksmith combinates it to your master key system. Example: 320201W-26-G3S.
• Uncombinated: a title word on the DL cores such as 320201T-26-DLQ. The description text on that core says sub-assembled, with pins included, not set, and no keys.

The title and the description on a few of these do not use the same word. I would treat uncombinated and sub-assembled as the same state on those cores, and call before ordering if your job depends on it. A combinated core is not what you want for a master-keyed building. You want sub-assembled, then a locksmith with the key system on file.

Finish codes

The two-digit code after the series number is the finish. From the titles: 26 is satin chrome, 05 is bright brass, 06 is satin brass, 09 is antique brass and 13 is oil rubbed bronze. The finish only shows on the face of the core, but a brass core in a chrome lever looks like a mistake, so match it to the hardware around it.

How to choose

• Replacing a core in an existing system: match the platform and keyway (00, G3, DL or 8E), the pin count and the finish. Do not change any of them.
• Adding to a master-keyed system: sub-assembled, so the pins can be set to your bitting.
• New high-security job calling out UL 437: Medeco3.
• Key control is the whole point: KeyMark.

We also have notes on how other brands letter their cores, such as the Sargent 6300 keyway letter and the Alarm Lock IC core letters. The full Medeco line and the LFIC core category are on the site.

Common questions

What is the difference between Medeco Biaxial, Medeco3 and KeyMark LFIC cores?

Biaxial is the original platform (00 keyway here). Medeco3 is UL 437 listed with an M3 sidebar (G3 and DL keyways). KeyMark is the restricted keyway program with factory-controlled keys (8E keyway).

Does a Medeco LFIC core fit my lock?

The listings say it fits Medeco LFIC-compatible locksets in Schlage, Corbin Russwin, Sargent and Yale housing formats. Verify your format first.

What does combinated mean on a Medeco core?

The core is pinned to a key change and ships with two operating keys and one control key. Sub-assembled cores ship with pins included but not set, and no keys.

How do I swap a Medeco LFIC core?

Pull the existing core with a control key and slide the new one in. The listing says no lock disassembly is needed.

Do 5-pin and 6-pin Medeco cores interchange?

No. Match the pin count of the system you are working on.