Interchangeable Cores & Key Systems

Small Format and Large Format Interchangeable Cores

An interchangeable core is a lock core that comes out of the lock with a control key, so you can rekey a door by swapping the core instead of taking the lock apart. PDQ makes small format (SFIC) and Schlage-format large format (LFIC) interchangeable cores, conventional and high security cylinders, and the VAULT patented keying system. Every core and cylinder can be keyed different, keyed alike or into a master key system, so one key plan covers your PDQ locks, deadbolts and exit device trim.

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Key Systems by Type

Start with how often you rekey, then decide how tightly you need to control the keys.

PDQ IC small format interchangeable core

Interchangeable Core · SFIC & LFIC

IC Interchangeable Cores

Pull the core with a control key and drop in a new one, without taking the lock off the door.

Small format cores in 6 or 7 pin fit Best, Falcon and Arrow housings; large format cores follow the Schlage format
Fits the MR mortise lock, GT cylindrical lock, KM, KV and MJ deadbolts, and 6W, 6N, 6C, 4EW and 4EN trim. See all commercial deadbolts.

Best for: Schools, campuses and multi-tenant buildings that rekey often

View IC Cores

Patented Keyway · SFIC

VAULT Patented Keying System

A tapered gate inside the core blocks every key except a VAULT key.

U.S. Patent #12338653, protected through 2044; only authorized distributors can supply VAULT keys and cores
7-pin cores drop into existing SFIC housings, and VAULT keys still run standard cores, so you can upgrade in phases; BHMA certified with a 5-year warranty

Best for: Campuses and portfolios that need closed-loop key control

View VAULT

PDQ HSC high security cylinder with sidebar keyway

High Security · Conventional

HSC High Security Cylinders

Two hardened anti-drill pins and a proprietary PDQ keyway with sidebar.

Key-in-knob/lever cylinders for PDQ cylindrical locks, plus a mortise/rim combo cylinder
Fits the GP, SD and CL locks, the KV deadbolt, and 6T, 6S, 4P and 4GW trim; keys are cut at the factory only

Best for: Exterior entries, server rooms and other high-risk doors

View HSC Cylinders

Conventional · Standard Security

Cylinder Lock Cores

Conventional pin tumbler cylinders for doors that stay keyed the same for years.

Key-in-knob/lever, mortise and rim cylinders; SCC (Schlage C compatible) keyway standard, with other keyways available
Fits the SF and XGT locks, the KT deadbolt, and 4EW, 6N, 6T, 4S and 4K trim

Best for: Interior offices, storage rooms and low-turnover doors

View Cylinders

Ordering · Literature

Keying Systems and Forms

The master key planning form, keying system worksheet and keying schedule in one PDF.

Lay out key levels, pin count, keyway and key control before you order
Use it for a new system or to add doors to an existing one

Best for: Anyone ordering a keyed or master keyed system

Download the Forms

Compare PDQ Interchangeable Cores and Cylinders

Product	Core Type / Format	Keyway	Key Control Level	Compatible PDQ Locks	Notes
IC Core (SFIC)	Small format IC, 6 or 7 pin	Best-compatible keyways; PDQ1, PDQ2, PDQ3	Open, exclusive or restricted	MR, GT, KM, KV, MJ; 6W, 6N, 6C, 4EW, 4EN trim	Swaps with Best, Falcon and Arrow cores
IC Core (LFIC)	Large format IC, Schlage format	SCC; TA restricted	Open or restricted	MR, KM, MJ	Does not swap with other brands' cores
VAULT	Small format IC, 7 pin	VAULT patented	Patented	Any PDQ or standard SFIC housing	Authorized distributors only; 5-year warranty
HSC High Security	Conventional key-in-knob/lever; mortise/rim combo	Proprietary PDQ keyway with sidebar	High security	GP, SD, CL, KV; 6T, 6S, 4P, 4GW trim	2 hardened anti-drill pins; factory-cut keys
Cylinder	Conventional key-in-knob/lever, mortise, rim	SCC standard; other brands' keyways and TA restricted	Open to restricted	SF, XGT, KT; 4EW, 6N, 6T, 4S, 4K trim	Rekey by repinning

Every PDQ core and cylinder can be keyed different, keyed alike or master keyed, and small format construction cores are available. A restricted keyway needs system approval before PDQ processes the order.

Key: SFIC = small format interchangeable core · LFIC = large format interchangeable core · SCC = Schlage C compatible · TA, PDQ3 = PDQ restricted keyways · PDQ1, PDQ2 = PDQ exclusive keyways

Ready to spec or order?

Need Certification Details?

See every UL, ANSI/BHMA and ADA listing for the PDQ locks and trim these cores fit in one filterable matrix.

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How to Choose a Key System

PDQ small format interchangeable core

Step 1

Decide how you will rekey

A conventional cylinder stays in the lock, so rekeying means taking the lock apart or repinning the cylinder, usually with a locksmith. An interchangeable core comes out with a control key, so staff can swap it in seconds. Small format interchangeable cores use a plug smaller than the standard 1/2" and swap with any SFIC brand, including Best, Falcon and Arrow. Large format cores use the same key families as conventional cylinders and stay with one manufacturer. Check the comparison table for which PDQ locks take each.

PDQ VAULT patented core

Step 2

Set the level of key control

Open keyways like SCC use blanks anyone can cut. Exclusive keyways (PDQ1 and PDQ2) use blanks that are hard to find. A restricted keyway (TA or PDQ3) needs a letter of authorization for keys, blanks and cylinders, and PDQ registers every key. The VAULT patented keyway adds patent protection through 2044 and sells only through authorized distributors. For doors that face forced entry, a high security lock cylinder adds anti-drill pins and a sidebar keyway.

PDQ master keys being etched

Step 3

Plan the master key system and order

A master key system lets one key open a group of doors while each door keeps its own change key. PDQ systems run from change key up to great grand master, and PDQ recommends no more than four levels. Map your doors on the planning form and keying schedule in the Keying Systems and Forms PDF, then send them with your order through your PDQ rep or distributor.

Read the Master Keying Guide

Where PDQ Key Systems Fit

Education

Campuses rekey often and run large master key systems. Small format cores let staff swap a core when a key goes missing. VAULT cores fit existing SFIC housings and VAULT keys still run standard cores, so a campus can upgrade one building at a time.

Education Solutions

Aerial view of North Georgia Medical Plaza, a two-story stone and brick medical office building with a covered entrance canopy, large windows, and a landscaped parking lot surrounded by trees.

Healthcare

Pharmacy, records and staff-only doors need tighter control than patient rooms. Put a restricted keyway, VAULT or HSC high security cylinders on those doors and standard cores everywhere else, under one master key system.

Healthcare Solutions

Upward-angled photo of the Willow apartment building at 161 Riverheath, showing a modern multi-story facade with white paneling, wood-tone siding, staggered balconies with cable railings, and large glass storefront entrance under a clear blue sky.

Property Management

Tenant turnover means constant rekeying. Interchangeable cores let maintenance staff swap a core between tenants without a locksmith, and a master key system gives managers one key per building.

Multifamily Solutions

Interchangeable Core and Key System FAQs

What is an interchangeable core?

An interchangeable core is a lock core that comes out of the lock with a control key, so you rekey a door by swapping the core instead of taking the lock apart. The lock stays on the door, and staff can restore security within seconds after a key is lost. PDQ makes small format and Schlage-format large format interchangeable cores, plus the VAULT patented core.

What is the difference between small format and large format interchangeable cores?

Small format interchangeable cores (SFIC) use a plug smaller than the standard 1/2" and swap with any other SFIC housing, including Best, Falcon and Arrow. Large format interchangeable cores (LFIC) use the same key families as conventional cylinders and usually only fit one manufacturer's locks. PDQ SFIC cores come in 6 or 7 pin, and PDQ LFIC cores follow the Schlage format.

What is a restricted or patented keyway?

A restricted keyway uses key blanks set aside for limited use, so keys and cylinders can only be ordered with authorization. PDQ's restricted keyways need a letter of authorization, every key is registered, and no blank keys are sold. A patented keyway adds legal protection: PDQ VAULT is covered by U.S. Patent #12338653 through 2044, and only authorized distributors can supply VAULT keys and cores.

How does a master key system work?

A master key system groups locks so one key opens many doors while each door keeps its own change key. Levels run from change key to master, grand master and great grand master keys, and PDQ recommends no more than four levels. Learn more in our guide to master keying.

Which PDQ locks accept interchangeable cores?

Most PDQ mortise locks, cylindrical locks, deadbolts and exit device trim accept interchangeable cores. Small format cores fit the MR mortise lock, GT cylindrical lock, KM, KV and MJ deadbolts, and 6W, 6N, 6C, 4EW and 4EN trim. The MR, KM and MJ also take Schlage large format cores. The KT deadbolt takes a conventional cylinder only.

How do I order a keyed or master keyed system from PDQ?

Fill out the Master Key System Planning Form and Keying Schedule in the Keying Systems and Forms PDF, then send them with your order through your PDQ rep or distributor. The forms cover key levels, pin count, keyway and key control. To add doors to an existing system, include your original PDQ sales order number.

Key System Guides

PDQ keys being etched for a master key system

Guide

Master Keying: The Key to Efficient Access Control

Read the Guide

Installing a small format interchangeable core into a door

Guide

The Role of Interchangeable Cores in Key Control and Access Management

Read the Guide

View All Guides

Complete the Opening

Key your locks and deadbolts into one system.

Commercial Mortise Locks

Grade 1 MR Series locks that take mortise cylinders, high security cylinders, or SFIC and Schlage large format cores.

View Mortise Locks

Commercial Deadbolts

Extra heavy, heavy and standard duty deadbolts, most ready for interchangeable cores.

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Need Help Planning a Key System?

Tell us about your doors and a PDQ rep will help you choose cores, keyways and key control, plan your master key system, and get submittals and pricing.