BEST 8K Series Grade 1 Heavy D...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$1,004.00
$619.44
BEST BEST 8K Series - Corridor/Apartment Function (C) Double Cylinder Grade 1 Heavy Duty Knob Lock, SFIC Less Core BEST-8K-C

BEST 8K Series Grade 1 Heavy Duty Corridor Function Double Cylinder Knob Lock

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Model: 8K37C4ASTK612
$1,004.00
$619.44
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$1,004.00
$619.44
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BEST 8K Series Grade 1 Heavy Duty Corridor Function Double Cylinder Knob Lock

Premium Grade 1 Cylindrical Knob Lock for Heavy-Duty Commercial Applications

The BEST 8K Series Grade 1 Heavy Duty Corridor Function Double Cylinder Knob Lock delivers dependable security for high-traffic commercial applications. This premium cylindrical knob set features knobs machined from solid brass or bronze bar stock with a 2 1/8" diameter and 9/16" throw deadlocking latch. Designed with a 2 1/16" diameter chassis to fit standard 2 1/8" door holes, the 8K Series exceeds ANSI Grade 1 requirements for security and reliability in demanding commercial environments.

Professional Features & Benefits

  • Grade 1 Heavy-Duty Construction: Exceeds ANSI Grade 1 requirements with knobs machined from solid brass or bronze bar stock for exceptional durability in high-traffic applications.
  • Standard Door Compatibility: 2 1/16" diameter chassis fits standard 2 1/8" door holes with adjustable door thickness from 1 3/8" to 2" standard.
  • Enhanced Security Design: Cores must be removed before keyed knobs to deter break-in attempts, with snap-on inside rose featuring no exposed screws for additional attack resistance.
  • Premium Materials: Internal parts are brass or corrosion-treated steel with brass or bronze roses reinforced with steel liner for long-term reliability.
  • Smooth Operation: Steel retractor with low friction bearings and long bearing length in chassis provide smooth, wear-resistant operation throughout the lock’s service life.
  • Flexible Installation Options: 2 3/4" standard backset with 3 3/4" and 5" options available, plus multiple rose styles including round 3 3/4" diameter and 2 9/16" diameter options.
  • Quick Rekeying Capability: BEST interchangeable core system allows for economical rekeying without lock replacement.
  • Optional Security Features: Available with breakaway feature to prevent overpowering by wrench, knurled knob option for accessibility applications, and spin-free knob feature for key-only operation.

Technical Specifications

  • Commercial/Residential: Commercial
  • Department: Door Hardware
  • Door Hand Direction: Non-Handed
  • Duty Level: Heavy Duty
  • Electronic: No
  • Grade: Grade 1
  • Handle Type: Knob
  • Keyed: No
  • Keyed Function: Double Cylinder
  • Product Attribute: Cylindrical Locks
  • Product Category: Mechanical Locks
  • Product Function: Corridor/Dormitory
  • Product Group: Mechanical Locks
  • Product Subgroup: Bored Locksets
  • Product Type: Knobsets
  • Series: 8K Series
  • Subcategory: Bored Locksets

Installation & Operation

  1. Review manufacturer specifications and verify door preparation requirements including door thickness (1 3/8" to 2" standard), 2 1/8" bore hole, and 1" latch hole dimensions.
  2. Use manufacturer-provided templates to mark mounting hole locations accurately on door and frame surfaces for proper backset alignment (2 3/4" standard).
  3. Prepare door by drilling required 2 1/8" diameter hole for chassis and 1" hole in door edge for latch housing.
  4. Install latch assembly and secure knob set chassis to door with threaded roses, ensuring proper alignment and door thickness adjustment.
  5. Adjust knob operation for smooth function and verify 9/16" throw deadlocking latch engagement with strike plate.
  6. Test lock operation with interchangeable core installed to verify proper function and make final adjustments as needed. Refer to manufacturer documentation for complete installation details and troubleshooting.

Professional Applications

  • Government and Military Facilities
  • Commercial Office Buildings
  • Educational Institutions
  • Healthcare Facilities
  • Multi-Tenant Residential Properties
  • Industrial and Warehouse Facilities
  • High-Traffic Commercial Entrances

Why Choose BEST Quality?

BEST 8K Series knob locks deliver professional-grade reliability with solid brass or bronze construction and Grade 1 certification that exceeds ANSI requirements for security and durability. The premium workmanship includes corrosion-treated internal components and carefully designed mechanisms that ensure reliable performance in demanding commercial applications where dependable security is essential.

Product Specs

Series:
8K Series
Grade:
Grade 1
Duty Level:
Heavy Duty
Keyed Function:
Double Cylinder
Product Group:
Mechanical Locks
Product Subgroup:
Bored Locksets
Product Type:
Knobsets
Subcategory:
Bored Locksets
Keyed:
No
Electronic:
No
Commercial/Residential:
Commercial
Handle Type:
Knob
Product Attribute:
Cylindrical Locks
Product Function:
Corridor/Dormitory
Door Hand Direction:
Non-Handed
Product Category:
Mechanical Locks
Department:
Door Hardware

BEST 8K37C4ASTK612 – Frequently Asked Questions

1) Will the BEST 8K Series knob lock fit a door already bored for a 2-1/8 inch hole?
Yes. The 8K chassis measures 2-1/16 inches in diameter and drops into the standard 2-1/8 inch bore, with a 1 inch hole in the door edge for the latch. That is the same prep most commercial cylindrical locks already sit in, so replacing an existing bored knob lock usually needs no new drilling. Backset is 2-3/4 inches standard, and a 5 inch backset is orderable for wide-stile or aluminum applications.
2) What door thickness does the BEST 8K knob lock cover?
1-3/8 to 2 inches as standard, which takes in the usual 1-3/4 inch commercial door and the thinner 1-3/8 inch interior doors in older buildings. For doors at the top of that range there is a 3-3/8 inch concave thick-door rose to order.
3) Does the BEST 8K knob lock come with cores, or do I have to order keys separately?
It ships less core. The 8K takes a BEST small format interchangeable core, which you supply keyed to your existing system, so the lock can go on the door before the keying is settled and be rekeyed later by pulling the core rather than replacing the lock. Budget for a core and control key per opening.
4) What is the closest Grade 1 heavy duty cylindrical knob lock to the BEST 8K Series from another manufacturer?
The Sargent 8XG04 is a Grade 1 heavy duty knob lock in the 8X Line Series with a 2-3/4 inch backset and a single cylinder, in a storeroom/closet function. The BEST 8K is also Grade 1 and heavy duty, and its corridor/dormitory function is a double cylinder arrangement, so the two differ in how the outside knob behaves: the 8XG04 storeroom outside knob is always locked and retracted by key only, while the corridor function uses cylinders on both sides. The 8K is offered in 2-3/4 inch and 5 inch backsets. Match the function to the opening before treating the 8XG04 as an equivalent.
5) I only need a knob that latches and never locks on a corridor door - what should I use instead of a keyed 8K?
The Corbin Russwin CK4310 is a Grade 1 passage/closet cylindrical lock with a Global knob in the CK4300 Series, fitting doors 1-3/8 inch to 2 inch. The Schlage D10S is also a Grade 1 heavy duty passage latch with an Orbit knob in the D Series. Both hold the same Grade 1 rating as the BEST 8K but carry no cylinder, where the 8K is a keyed corridor/dormitory double cylinder set. On a door that only needs to latch, either passage set removes the keying entirely.
6) Is a Grade 2 knob lock enough for a commercial corridor, or do I need the BEST 8K?
The Sargent 6G04 is a Grade 2 standard duty storeroom/closet knob lock with a single cylinder in the 6 Line Series, and the Corbin Russwin CK4410 is a Grade 2 passage/closet knobset fitting doors 1-3/8 inch to 1-3/4 inch. The BEST 8K is Grade 1 and heavy duty, with a chassis and knobs built for high-traffic commercial openings. Where a specification or facility standard calls for ANSI Grade 1, the Grade 2 sets above do not meet it; where the opening carries lighter traffic and the spec allows Grade 2, they are the lighter-duty route.
7) Which knob lock should I use if the door is thicker than 1-3/4 inches?
The BEST 8K adjusts from 1-3/8 inch to 2 inch as standard and offers a 3-3/8 inch concave thick-door rose. Among comparable knob locks, the Falcon X101 covers 1-3/8 inch to 2-1/4 inch and the Corbin Russwin CK4310 covers 1-3/8 inch to 2 inch, both Grade 1. The Dexter C2000 sets and the Cal-Royal Barrington knob locks stop at 1-3/4 inch. On a thick door, confirm the range before ordering; the 8K and the two Grade 1 peers above are the sets that reach past 1-3/4 inch.
8) Do I need to worry about handing when ordering an 8K knob lock?
No. The 8K is non-handed, so one part number works on a left or right hand door and you do not have to survey every opening before placing a fleet order. Decide backset, rose, knob style, finish and strike instead.
9) Is a Grade 1 knob lock overkill for an apartment building corridor door?
For an apartment or dorm entry cycling all day, Grade 1 is the tier that holds up; the 8K is heavy duty with knobs machined from solid brass or bronze bar stock and internal parts of brass or corrosion-treated steel. Grade 2 and Grade 3 knob locks are built for lighter cycle counts. If the opening is low traffic, a Grade 2 option like the Corbin Russwin CK4410 or a Grade 3 like the Cal-Royal BER00 costs less to standardize on, but neither is a corridor-function double cylinder.
10) What do I have to specify to order a BEST 8K corridor knob lock correctly?
Five choices settle the order: backset (2-3/4 inch standard or 5 inch), knob style (round or tulip), rose (2-9/16 inch concave, 3-3/8 inch concave, 3-3/8 inch concave thick door, or 3-3/8 inch convex), strike (ANSI or standard), and finish. Cores are separate.
11) What finishes does the BEST 8K knob lock come in, and is there anything for a healthcare facility?
Ten finishes: 605 bright brass, 606 satin brass, 611 bright bronze, 612 satin bronze, 613 satin bronze oil-rubbed, 619 satin nickel, 625 bright chrome, 626 satin chrome, 626AM satin chrome antimicrobial, and 690 statuary dark bronze. For patient rooms and clinical corridors the 626AM antimicrobial satin chrome is the one to specify; it matches plain 626 visually so it can be mixed into a building already standardized on satin chrome.
12) Which knob lock should I use on an aluminum storefront stile?
Order the 8K with the 5 inch backset for a wide stile aluminum door; the 2-3/4 inch standard backset is for normal wood and hollow metal doors and will put the knob too close to the glass on a storefront. Check the stile will take the 2-1/8 inch bore before committing.
13) Which Grade 1 knob lock uses an interchangeable core like the BEST 8K does?
The Falcon X101 is a Grade 1 heavy duty cylindrical knobset with an interchangeable core, fire rated, in the X Series, and it fits doors 1-3/8 inch to 2-1/4 inch. It is a passage function, so it does not lock at all. The BEST 8K carries the interchangeable core system for rekeying without replacing the lock and is a keyed corridor/dormitory function. If the requirement is core-interchangeable hardware on a keyed opening, the X101 passage function will not cover it; if the opening is a corridor door that only needs to swing free, the X101 is the simpler part.
14) Will a Kwikset or Schlage Residential knob work as a substitute for the BEST 8K on an apartment corridor door?
The Kwikset 400P-CP is a Grade 3 keyed entrance knob for doors 1-3/8 inch to 1-3/4 inch, and the Schlage Residential F500 Plymouth with Georgian knob is an F Series combo pack with adjustable backsets for the same 1-3/8 inch to 1-3/4 inch range. The BEST 8K is a commercial Grade 1 heavy duty knob lock with an interchangeable core and a 1-3/8 inch to 2 inch door thickness adjustment. These are different classes of hardware: the residential sets carry a conventional cylinder and a lighter grade, so they will not drop into a keyway system built around BEST cores, and a Grade 1 spec will not accept them.
15) What is the difference between the BEST 8K corridor function and a classroom or entrance/office knob lock?
The Dexter C2000 classroom knob lock is a Grade 2 keyed non-clutching ball knob set for doors 1-3/8 inch to 1-3/4 inch, where the outside knob is locked and unlocked by key from outside only. The Corbin Russwin CK4851 is an entrance/office knob lock in the 4000 Series with a conventional cylinder, fitting 1-3/8 inch to 2 inch doors, where a button or turn inside sets the outside knob. The BEST 8K corridor/dormitory function is a double cylinder set, keyed from both sides with no inside button. For a dormitory or apartment corridor where control must stay with the key on both faces, that is the distinction that matters.
16) I need a fire rated knob lock - which knobsets carry a fire rating?
The Falcon X101 is a Grade 1 heavy duty interchangeable core knobset with a fire rating, and the Falcon W101 is a Grade 2 medium duty passage/closet latch knob with a 2-3/4 inch backset that is also fire rated. Both are passage functions with no cylinder. The BEST 8K is a Grade 1 heavy duty keyed corridor/dormitory set available with a 2-3/4 inch backset. On a rated opening that also needs keying, confirm the listed rating for the exact 8K configuration with the manufacturer documentation before submitting it.
17) Is the Sargent 28C knob trim an alternative to a BEST 8K knob lock?
The Sargent 28C-KNOB is exit device trim with a knob and rose in the 28 Series, sized for 1-3/4 inch doors, and the Sargent 78-2875 is an outside knob only with B design in the 7800 Series. Both are trim that mounts to an exit device rather than a self-contained lock. The BEST 8K is a complete cylindrical knob lock with its own chassis and latch. If the door already carries a panic device, the trim is what you order; if the door is a plain bored opening, the 8K is the set that does the whole job.
18) Which knob lock should go on the bathroom or bedroom door instead of a corridor function?
For a privacy opening, the Dexter C2000 privacy knob is a Grade 2 non-keyed ball knob set for 1-3/8 inch to 1-3/4 inch doors, the Cal-Royal BER20 is a Grade 3 privacy knob lock with brass trim for the same range, and the Pamex FTF Baron privacy knob is Grade 3 for 1-3/8 inch to 1-3/4 inch. All three lock from inside with no key on the outside. The BEST 8K is a keyed corridor/dormitory double cylinder set built for commercial traffic, which is the wrong function for a bath or bedroom door.
19) Can I get a knurled knob on the 8K for a hazardous room?
Yes, knurled knobs are an available option on the 8K, which is what you specify where a tactile warning is wanted on doors to mechanical, electrical or chemical storage rooms. Two other options exist on the series: a breakaway feature so the knob cannot be overpowered with a wrench, and a spin-free knob for key-only operation.
20) Are the knobs on the 8K big enough to cover an old prep, and can the rose hide the scarring?
Knobs are 2-1/8 inches in diameter. Coverage on the door face comes from the rose, and the 3-3/8 inch options (concave or convex) give the widest footprint over an existing prep, while the 2-9/16 inch concave rose is the tighter, more modern look. The inside rose snaps on with no exposed screws.
21) A dummy knob looks the same as the 8K - can I use one to fill a spare door?
A dummy knob has no latch and no chassis: the Schlage A170 single dummy trim is a Grade 2 non-keyed dummy for doors 1-3/8 inch to 1-7/8 inch, and the Cal-Royal BA40 is a dummy knob for 1-3/8 inch to 1-3/4 inch doors. The BEST 8K is a working cylindrical lock with a 2-1/16 inch chassis fitting a 2-1/8 inch bore, a 9/16 inch throw deadlocking latch, and cylinders on both sides. A dummy will match the look on an inactive leaf but will not latch or lock, so it is not a substitute on any door that has to secure.
22) What is a keyless alternative to a keyed knob lock on a back corridor door?
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 runs on a code rather than a key, so there is nothing to carry and nothing to rekey when staff change. The BEST 8K takes a key on both sides and uses an interchangeable core so the opening can be rekeyed without pulling the lock. Choose the 3830 where you want to avoid issuing keys, and the 8K where the opening has to sit inside an existing keyed system.
23) Can I standardize a whole building on one knob and match finishes across mixed hardware?
The BEST 8K comes in ten finishes including 605 bright brass, 626 satin chrome, 626AM satin chrome antimicrobial, 619 satin nickel and 690 statuary dark bronze, in round and tulip knob styles, with concave and convex roses and ANSI or standard strikes. Among Grade 1 knob peers, the Sargent 8XG04 storeroom and the Schlage D10S passage set can carry other functions on the same building. When mixing brands across a facility, confirm the finish code on each brand against the same ANSI/BHMA number rather than the brand's finish name, and hold one keyway family for all keyed openings.
How fast can I get the BEST 8K37C4ASTK612 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 BEST 8K37C4ASTK612 come with a warranty?
Absolutely. The BEST 8K37C4ASTK612 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 BEST 8K37C4ASTK612?
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
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