Name: Corbin Russwin CK4355 Classroom Cylindrical Lock - Grade 1, Global Knob, Keyed
Brand: Corbin Russwin
SKU: CK4355 GRD 630
Price: 735.28 USD
Availability: InStock

Product Overview
FAQs

Corbin Russwin CK4355-KEYED Classroom Cylindrical Lock Grade 1 with Global Knob, Keyed Single Cylinder

Heavy-Duty Commercial Classroom Lock for High-Traffic Institutional Applications

The Corbin Russwin CK4355-KEYED is a Grade 1 classroom cylindrical lock from the CK4300 Series, engineered for demanding commercial, industrial, and institutional environments. This keyed single-cylinder knobset features a deadlocking latchbolt operable by knob from either side, except when the outside knob is locked by key — the inside knob remains always free for safe egress. Designed to fit door thicknesses from 1-3/8" to 2" with a 2-3/4" backset, it includes a conventional 6-pin cylinder and two nickel silver keys. Heavy wrought knobs are lined with steel for impact resistance, and internal parts are zinc dichromate plated for corrosion resistance, making this lock a reliable choice for schools, hospitals, hotels, and other high-use facilities.

Professional Features & Benefits

Door Thickness Compatibility: Accommodates door thicknesses from 1-3/8" to 2", providing versatile fit across a wide range of commercial door applications.
Precise Backset: Standard 2-3/4" backset with a 787F66 deadlocking latch featuring a square corner front measuring 2-1/4" x 1-1/8" universal configuration for reliable latching performance.
ANSI Curved Lip Strike Included: Comes with an ANSI curved lip strike measuring 4-7/8" x 1-1/4" x 1-1/4" lip to center for secure and code-compliant door frame engagement.
Impact-Resistant Heavy Wrought Knobs: Steel-lined heavy wrought knobs deliver exceptional durability and impact resistance for high-traffic institutional and commercial environments.
Corrosion-Resistant Internal Components: Internal parts are zinc dichromate plated to resist corrosion, extending service life in demanding applications.
1/2" Stainless Steel Throw Latchbolt: Features a 1/2" (13mm) stainless steel throw latchbolt for dependable deadlocking performance and long-term durability.
Conventional 6-Pin Cylinder: Includes a conventional 6-pin cylinder with two nickel silver keys for reliable keying and key control compatibility.
Non-Handed Design: Non-handed configuration simplifies installation and reduces inventory requirements for facilities managers and contractors.
Manufacturer Warranty: Backed by a 3-year manufacturer warranty for added confidence and protection.

Technical Specifications

Subcategory: Cylindrical Locks
Product Group: Mechanical Locks
Series: CK4300 Series
Grade: Grade 1
Keyed Function: Single Cylinder
Standard Latch: 787F66 - Deadlocking 2-3/4" Backset, Square corner front, 2-1/4" x 1-1/8" universal
Standard Strike: ANSI Curved Lip 4-7/8" x 1-1/4" x 1-1/4" lip to center
Warranty: 3 Year
ANSI/BHMA: F84
Product Subgroup: Bored Locksets
Product Type: Knobsets
Keyed: Yes
Fasteners: Wood and Machine Screws
Commercial/Residential: Commercial
Function Description: Deadlocking latchbolt by knob either side, except when key outside locks outside knob. Outside knob unlocked by key outside
Lock Type: Cylindrical
Handle Type: Knob
Lock Function: Classroom
Product Attribute: Cylindrical Locks
Product Model: CK4355
Product Function: Classroom
Door Hand Direction: Non-Handed
Door Thickness Range: 1-3/8" to 2"
Product Category: Mechanical Locks
Backset (Distance): 2-3/4"
Department: Door Hardware

Professional Applications

Schools and Educational Facilities
Hospitals and Nursing Homes
Hotels and Hospitality Properties
Apartment and Multi-Tenant Residential Buildings
Municipal and Government Buildings
Airports and Transportation Facilities
Retail Complexes and Commercial Offices
Churches and Institutional Facilities
Industrial and Warehouse Environments

Why Choose Corbin Russwin Quality?

Corbin Russwin CK4300 Series cylindrical locks deliver professional-grade reliability with heavy wrought steel-lined knobs, zinc dichromate-plated internal components for corrosion resistance, and a 1/2" (13mm) stainless steel throw latchbolt built for long-term performance. The CK4355-KEYED meets Grade 1 commercial standards and ANSI/BHMA F84 classification, and is backed by a 3-year manufacturer warranty. Engineered for demanding commercial applications — from schools and hospitals to airports and warehouses — where dependable classroom security is essential.

Manufacturer Resources

Dummy Trim Knob Lock Installation Instructions

Product Specs

Subcategory:: Cylindrical Locks
Product Group:: Mechanical Locks
Series:: CK4300 Series
Grade:: Grade 1
Keyed Function:: Single Cylinder
Standard Latch:: 787F66 - Deadlocking 2-3/4" Backset, Square corner front, 2-1/4" x 1-1/8" universal
Standard Strike:: ANSI Curved Lip 4-7/8" x 1-1/4" x 1-1/4" lip to center
Warranty:: 3 Year
ANSI/BHMA:: F84
Product Subgroup:: Bored Locksets
Product Type:: Knobsets
Keyed:: Yes
Fasteners:: Wood and Machine Screws
Commercial/Residential:: Commercial
Function Description:: Deadlocking latchbolt by knob either side, except when key outside locks outside knob. Outside knob unlocked by key outside
Lock Type:: Cylindrical
Handle Type:: Knob
Lock Function:: Classroom
Product Attribute:: Cylindrical Locks
Product Model:: CK4355
Product Function:: Classroom
Door Hand Direction:: Non-Handed
Door Thickness Range:: 1-3/8" to 2"
Product Category:: Mechanical Locks
Backset (Distance):: 2-3/4"
Department:: Door Hardware

Corbin Russwin CK4355 GRD 630 – Frequently Asked Questions

1) Will the Corbin Russwin CK4355 classroom knob lock fit a 1-3/4 inch metal door with a 2-3/4 inch backset prep?

Yes. The CK4355 is built for a 2-3/4 inch backset and covers door thicknesses from 1-3/8 inch to 2 inch, so a standard 1-3/4 inch commercial door sits right in the middle of the range. It also handles thicker doors up to 2 inch without a separate kit, which is more range than most cylindrical knobsets give you. The lock is non-handed, so you do not specify left or right when you order.

2) How does a classroom function lock actually work, and is the inside knob ever locked?

On the CK4355 the inside knob is always free. Both knobs retract the deadlocking latchbolt normally; a key on the outside locks the outside knob, and the same key outside unlocks it again. There is no button and no way to lock the inside, so egress is never blocked. That is the difference from a storeroom function, where the outside is permanently locked, and from an office/entry function, where someone can lock up from inside the room.

3) Will the Corbin Russwin CK4355 latch into the strike already in my frame, or do I need to change the prep?

It ships with an ANSI curved lip strike, 4-7/8 x 1-1/4 inches with a 1-1/4 inch lip to center, so if your frame already carries the ANSI 4-7/8 inch strike prep common on hollow metal frames, it drops straight in. The latch is the 787F66 deadlocking unit with a square corner front, 2-1/4 x 1-1/8 inch, and a 1/2 inch stainless steel throw. If your existing frame has a round corner or full lip residential strike, plan on re-prepping the frame to the ANSI cutout.

4) What do I have to specify when ordering the CK4355, and what is the LC option?

Three decisions. First, cylinder: the standard build comes with a conventional 6-pin cylinder in the L4 keyway and two nickel silver keys, or you order LC, less conventional cylinder, which ships the lock without a cylinder so you can install your own to match an existing key system. Second, finish: 605 bright brass, 613 satin bronze oil-rubbed, or 630 satin stainless. Third, keying: keyed different is standard, or keyed alike if you want a group of locks on one key. There is also a free-text field for special keying requirements.

5) I need one key to open every classroom door in the building. Can these be keyed alike?

Yes, keyed alike is a selectable option on the CK4355 when you order, alongside the standard keyed different. Pick keyed alike and the group ships on a common key. If you are matching an existing Corbin Russwin key system already in the building, order the LC version without a cylinder instead and have your locksmith fit cylinders from your own system. There is also a text field for special cylinder and keying requirements if the job needs master keying spelled out.

6) Is the Corbin Russwin CK4355 a Grade 1 lock, and what ANSI function number is it?

Grade 1, and it carries the ANSI/BHMA F84 function classification, which is the classroom lock designation. For a spec writer or an institutional buyer standardizing a school or hospital, F84 plus Grade 1 is what goes on the hardware schedule. The knobs are heavy wrought and steel lined for impact resistance, and internal parts are zinc dichromate plated against corrosion.

7) I need a lock where staff can lock the door from inside the room. Is the CK4355 the right one?

No. On the CK4355 the inside knob is always free and cannot be locked, and the outside knob is locked only by key from the outside. If the requirement is locking from inside the room, look at an entrance or office function instead, such as the BEST 8K Series Grade 1 entrance function knob or the Dexter C2000 Series entry/office knob. Note that many districts now specifically want the classroom function precisely because the inside never locks, so confirm the intent before switching.

8) What is the closest Grade 1 heavy duty alternative to the Corbin Russwin CK4355 classroom knob lock?

For a Grade 1 heavy duty knob lock in the same weight class, the Sargent 8XG04 from the 8X Line Series is a storeroom/closet single cylinder knob lock with a 2-3/4 inch backset, matching the CK4355 backset. The functional difference matters: the CK4355 is a classroom function, where the deadlocking latchbolt works by knob from either side except when the key outside locks the outside knob. The 8XG04 is storeroom function, where the outside knob stays locked at all times and the key retracts the latch. Choose the CK4355 when a teacher or staff member needs to lock the door from the corridor side with a key and leave it locked; choose the 8XG04 when the opening should never be left unlocked.

9) What looks like a substitute for the CK4355 but will not work on a keyed classroom door?

Dummy trim is the common mistake. The BEST 6K Series single dummy trim and the Schlage A170 single dummy trim are non-keyed knob trim with no latch and no cylinder - they are pull-only trim for an inactive leaf. The Sargent 78-2875 outside knob only with B design is likewise trim, not a complete lock. The CK4355 is a keyed single cylinder lock with a deadlocking latchbolt and a 787F66 deadlocking latch with a 2-1/4 inch by 1-1/8 inch square corner front, so none of the dummy trims will latch or secure the opening.

10) My door is 2 inches thick - which knob locks will actually fit?

Door thickness narrows the field fast. The Corbin Russwin CK4355 covers 1-3/8 inch to 2 inch. Among comparable commercial knobs, the Falcon X101 passage knobset goes to 2-1/4 inch, which also clears a 2 inch leaf. Most of the Grade 2 and Grade 3 knobs stop short: the Dexter C2000 classroom knob, the Arrow MK01 and RK01 passage knobs, and the Cal-Royal BER00 entrance/office knob are all rated 1-3/8 inch to 1-3/4 inch. For a keyed classroom function on a 2 inch door, the CK4355 is the one in this group that carries the range.

11) I need classroom function on a door with an exit device - does the CK4355 work?

No. The CK4355 is a bored cylindrical lock with a 2-3/4 inch backset and a 787F66 deadlocking latch, installed into a standard bored door prep. A door already carrying an exit device needs trim instead, and the Sargent 28C-KNOB exit device trim with knob and rose is a classroom function trim sized for 1-3/4 inch doors. Use the CK4355 where the opening takes a cylindrical lock, and the 28C-KNOB where the latching is handled by the exit device.

12) Should I use a knob lock or a lever for a classroom door?

The CK4355 is a knob design, and that is the deciding factor for a lot of jobs: many jurisdictions require lever operation on doors in the accessible path of travel, and a knob will not satisfy that. Where a knob is acceptable, it is harder to force open by leaning on it and less prone to being caught by a backpack strap in a school corridor. Check the requirement for the opening before you commit to a knobset; if the door needs a lever, the CK4355 is not the part.

13) What is a cheaper alternative to the Corbin Russwin CK4355 for a classroom door?

The Dexter C2000 Series classroom cylindrical ball knob lock is the closest lighter-duty substitute, a Grade 2 keyed classroom knob covering 1-3/8 to 1-3/4 inch doors. The tradeoff is real: Grade 2 rather than Grade 1, and it stops at 1-3/4 inch, so it will not cover a 2 inch door the way the CK4355 does. For a low-traffic interior classroom in a private school it is a sensible step down. For a public school corridor or a hospital, stay with Grade 1.

14) What other Grade 1 commercial knob locks could I use instead of the Corbin Russwin CK4355?

Three Grade 1 knob options sit alongside it. The Sargent 8XG04 is a heavy duty Grade 1 storeroom/closet single cylinder knob on a 2-3/4 inch backset, the same backset, but storeroom function means the outside is always locked and needs a key every time. The BEST 8K Series is a Grade 1 heavy duty entrance function single cylinder knob. The Falcon X101 is a Grade 1 heavy duty passage knobset with interchangeable core covering 1-3/8 to 2-1/4 inch doors, but passage function does not lock at all. Only the CK4355 among these is a classroom function.

15) Does the Corbin Russwin CK4355 come with mounting screws, or do I need to buy hardware separately?

Fasteners are included, both wood and machine screws, so the lock covers a hollow metal frame door and a wood door without a separate screw pack. The latch and the ANSI curved lip strike are in the box as well. What you supply is the door prep itself and, if you ordered the LC version, the cylinder.

16) Is the Corbin Russwin CK4355 handed, and does that change what I order for a right hand reverse door?

Handing does not apply. The CK4355 is non-handed, so one part number covers left hand, right hand, and reverse bevel openings. For a property manager or facility stocking spares, that means a single SKU on the shelf instead of four, and no wrong-hand returns.

17) The door does not need to lock at all - what should I use instead of a classroom lock?

When the opening only needs to latch, a passage knob drops the cylinder entirely. At Grade 1 the Falcon X101 is a heavy duty cylindrical passage knobset with an interchangeable core and covers doors 1-3/8 inch to 2-1/4 inch, and the Schlage D10S Orbit knob is a Grade 1 heavy duty passage latch. At Grade 2 the Falcon W101 is a medium duty passage/closet latch with a 2-3/4 inch backset, the same backset the CK4355 uses. All of these are non-keyed, so no key control or keying decision is involved.

18) Can I use an entrance function knob lock instead of the classroom CK4355?

Entrance function changes who controls the lock. The BEST 8K Series entrance function single cylinder knob is Grade 1 heavy duty, and the Dexter C2000 entry/office ball knob is Grade 2 keyed for doors 1-3/8 inch to 1-3/4 inch. Entrance function typically locks from the inside knob or button, so an occupant can secure the door without a key. On the CK4355, the outside knob is locked by key from the outside and unlocked by key from the outside, with the inside knob always free. If facility policy is that only keyholders decide the lock state, the classroom function CK4355 is what the spec calls for.

19) What is the difference between the Corbin Russwin CK4355 and the Sargent 6G04 storeroom knob?

The Sargent 6G04 is a Grade 2 standard duty storeroom/closet knob lock with a single cylinder, from the 6 Line Series. The CK4355 is Grade 1 with a classroom function, carrying ANSI/BHMA F84 and a 2-3/4 inch backset. Two things separate them: grade, where the CK4355 sits a tier up, and function, where storeroom keeps the outside knob permanently locked while classroom lets a keyholder leave the outside knob unlocked for normal use. Storage rooms, janitor closets and IT rooms suit the 6G04; occupied rooms that switch between open and secured suit the CK4355.

20) Are residential knob locks an acceptable substitute for the CK4355 on a commercial opening?

They are built to a different standard. The Kwikset 400P-CP keyed entry knob is Grade 3 for doors 1-3/8 inch to 1-3/4 inch, the Master Lock BC Series biscuit knob keyed entry is Grade 3, and the Cal-Royal BER00 entrance/office knob is Grade 3. The CK4355 is a commercial Grade 1 lock carrying ANSI/BHMA F84, with heavy wrought steel-lined knobs and zinc dichromate plated internals. On a school, hospital or municipal opening where the drawing calls out Grade 1 commercial hardware, a Grade 3 residential knob will not satisfy the spec.

21) The room needs to lock from inside for occupant privacy, not by key - what replaces the CK4355?

A privacy function knob is the right part. The Dexter C2000 privacy ball knob is Grade 2 non-keyed for doors 1-3/8 inch to 1-3/4 inch, the Cal-Royal BER20 is a Grade 3 privacy knob with brass trim for the same thickness range, and the Pamex FTF Baron knob privacy lockset is Grade 3 for 1-3/8 inch to 1-3/4 inch. These lock from the inside with no key on the outside. The CK4355 works the other way: the outside knob is locked and unlocked by key from the outside, and the inside knob is always free for egress.

22) Is there a keyless option instead of issuing keys for a CK4355 opening?

The Lockey 3830 is a mechanical keyless combination knob lock with an auto-locking passage function, fitting doors 1 3/16 inch to 2 inch. It removes key issue and rekeying from the equation entirely, which suits a shared room where the user group changes often. The CK4355 goes the other direction: it is a keyed single cylinder lock with a conventional 6-pin cylinder, orderable keyed different or keyed alike, so it folds into an existing master key system across a facility.

23) Will the CK4355 match the finish on the rest of the doors in my building?

Three finishes are offered: 605 bright brass, 613 satin bronze oil-rubbed, and 630 satin stainless steel. For a commercial or institutional building, 630 satin stainless is the one that matches most existing commercial hardware. 605 is the polished brass look and 613 the dark oil-rubbed bronze. Each of the three is available with either the standard 6-pin L4 cylinder or as LC, less cylinder.

How fast can I get the Corbin Russwin CK4355 GRD 630 delivered?

Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.

Can I return it if it doesn’t work for me?

Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.

Does the Corbin Russwin CK4355 GRD 630 come with a warranty?

Absolutely. The Corbin Russwin CK4355 GRD 630 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.

How do I get technical support or installation help for the Corbin Russwin CK4355 GRD 630?

You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us

Why buy the Corbin Russwin CK4355 GRD 630 from ZenSupply?

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Corbin Russwin CK4355 Classroom Cylindrical Lock - Grade 1, Global Knob, Keyed

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