BEST 8K Series Double Cylinder...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$971.00
$560.65
BEST BEST 8K Series - Special Function (DR) Double Cylinder Grade 1 Heavy Duty Knob Lock, SFIC Less Core BEST-8K-DR

BEST 8K Series Double Cylinder Grade 1 Heavy Duty Knob Lock with SFIC Core

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Model: 8K37DR4ASTK626
$971.00
$560.65
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$971.00
$560.65
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BEST 8K Series Double Cylinder Grade 1 Heavy Duty Knob Lock with SFIC Core

Premium Heavy-Duty Cylindrical Knob Lock for High-Traffic Commercial Applications

The BEST 8K Series delivers dependable security in high-traffic commercial environments with Grade 1 heavy-duty construction. This double cylinder knob lock features knobs machined from solid brass or bronze bar stock with a 2 1/8" diameter and 2 7/8" projection from door. Designed with a 2 1/16" diameter chassis to fit 2 1/8" door holes and adjustable for door thickness from 1 3/8" to 2" standard, with special E trim available for 2 1/8" to 3" doors. The 9/16" throw deadlocking latch provides reliable security performance.

Professional Features & Benefits

  • Grade 1 Heavy-Duty Construction: Exceeds ANSI Grade 1 requirements for security and reliability with knobs machined from solid brass or bronze bar stock for exceptional durability.
  • Adjustable Door Compatibility: Standard adjustment from 1 3/8" to 2" door thickness with special E trim available for 2 1/8" to 3" doors for versatile installation options.
  • 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 tamper resistance.
  • SFIC Interchangeable Core System: Quick, economical rekeying with BEST interchangeable core technology for efficient key management and security updates.
  • Precision Engineering: 2 1/16" diameter chassis fits 2 1/8" door holes with steel retractor featuring low friction bearings for smooth, wear-resistant operation.
  • Rotating Knob Face: Provides easy hand of door change without removing the knob, with no keeper hole on keyed knobs for added security.
  • Corrosion-Resistant Components: Internal parts are brass or corrosion-treated steel with friction insert inside rose to resist loosening for long-term reliability.
  • Optional Breakaway Feature: Prevents the lockset from being overpowered by a wrench for enhanced vandal resistance in vulnerable applications.

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: Special
  • 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 from 1 3/8" to 2" standard, with 2 1/8" bore hole and 1" edge hole requirements.
  2. Use manufacturer-provided templates to mark mounting hole locations accurately on door and frame surfaces for proper chassis and latch alignment.
  3. Prepare door by drilling 2 1/8" diameter hole for chassis and 1" hole in door edge for latch housing per manufacturer specifications.
  4. Install chassis, latch assembly, and strike hardware securing all components to door and frame per manufacturer torque specifications.
  5. Adjust knob operation and latch alignment for proper 9/16" throw engagement and smooth operation throughout the full range of motion.
  6. Test device operation to verify proper function, core installation, 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
  • Industrial and Warehouse Buildings
  • Multi-Tenant Residential Properties
  • International Projects Without ADA Requirements

Why Choose BEST Quality?

BEST 8K Series knob locks deliver professional-grade reliability with solid brass or bronze construction and Grade 1 heavy-duty performance that exceeds ANSI requirements. The precision-machined components and corrosion-resistant internal parts ensure dependable operation in demanding commercial applications. Engineered for strength, security, and long-term performance where reliable access control 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:
Special
Door Hand Direction:
Non-Handed
Product Category:
Mechanical Locks
Department:
Door Hardware

BEST 8K37DR4ASTK626 – Frequently Asked Questions

1) What door prep does a BEST 8K cylindrical knob lock need?
Standard commercial bored prep: a 2-1/8 inch cross bore through the face and a 1 inch hole in the door edge for the latch. The chassis itself measures 2-1/16 inch diameter so it drops into a 2-1/8 inch bore. Backset is either 2-3/4 inch standard or 5 inch if the door has a wide stile or a deep prep, and both strike options (ANSI or standard) are order choices, so match the strike to what is already cut into your frame.
2) Is the BEST 8K knob lock handed? I'm ordering for a mix of left and right doors.
Non-handed, so one part number covers both. The knob face rotates to change hand of door without pulling the knob off, which means a locksmith can field-adjust on the opening instead of stocking two versions. For a property manager buying across a building, that is one line item instead of two.
3) Does the BEST 8K double cylinder knob lock come with a core, or do I order cores separately?
It is built for BEST small format interchangeable cores and ships less core, so you supply cores from your own keying system. That is the point of the design for a facility already on BEST SFIC: you drop your own cores in with a control key and the lock is keyed into the existing masterkey system the same day. Double cylinder means it takes a keyed core on both sides, so budget two cores per lock.
4) Will a 9/16 inch latch throw work with the strike already in my frame?
The 8K uses a 9/16 inch throw deadlocking latch, which is standard cylindrical latch throw and engages a normal commercial strike lip. Where it matters is which strike you order: ANSI strike matches a 4-7/8 inch ANSI frame prep, the standard strike suits a smaller cut. If your frames are already ANSI prepped, order the ANSI strike and you reuse the existing cutout.
5) Is the BEST 8K knob lock Grade 1, and does that matter for a school or hospital corridor?
Grade 1, heavy duty, commercial rated. For high cycle openings, classroom corridors, patient wings, dorms, that is the tier a spec writer normally calls out. Knobs are machined from solid brass or bronze bar stock and the internal parts are brass or corrosion treated steel, with a steel retractor running on low friction bearings. One caveat for a US institutional buyer: a knob is not an ADA compliant operating device, so on doors subject to accessibility requirements you need a lever.
6) What is the closest Grade 1 heavy duty knob lock to the BEST 8K Series if BEST cores are not being used on the job?
The Sargent 8XG04 is a Grade 1 heavy duty knob lock in the 8X Line Series with a 2-3/4 inch backset, in storeroom function with a single cylinder. It matches the BEST 8K on grade and duty level, both being Grade 1 heavy duty knob locks, and the 8K also offers a 2-3/4 inch backset. The difference is keying architecture and function: the 8K here is a double cylinder special function built around a BEST small format interchangeable core, while the 8XG04 is a single cylinder storeroom lock. Choose by whether the opening needs key control on both sides or a keyed outside with a fixed-latch inside.
7) Which Grade 1 knob lock takes an interchangeable core and is fire rated for a labeled opening?
The Falcon X101 is a Grade 1 heavy duty cylindrical knob lock with an interchangeable core, carries a fire rating, and covers doors from 1-3/8 inch to 2-1/4 inch. It is a passage/closet function, so it has no keyed control - the latch retracts from both sides at all times. The BEST 8K Series is also Grade 1 heavy duty and uses a small format interchangeable core, but in double cylinder special function it is key operated. Where the labeled door needs a fire rated Grade 1 knobset with no locking, the X101 is the one to spec; where the opening needs key control, stay with the 8K.
8) What should be used instead of a knob lock on an opening that has to meet ADA?
None of the knob locks in this comparable range are lever operated - the BEST 8K Series, the Sargent 8XG04, the Falcon X101 and the Corbin Russwin CK4310 are all knob designs, and the 8K itself is specified for international projects without ADA requirements. For an ADA accessible opening the correct move is a lever operated cylindrical lock rather than any of these knobsets. Knob locks remain appropriate for government, industrial, and multi-tenant openings where a knob is acceptable, and for retrofits into existing knob prepped doors.
9) Is a double cylinder knob lock the right choice, or should I use a storeroom function?
Double cylinder means keyed on both sides, so nobody passes through in either direction without a key. That suits vaults, mechanical rooms, and stairwell doors where you want to control egress-side access too. It is not right for a door in a required egress path, and it is a heavier answer than most openings need. If you only need the outside secured with free egress inside, a storeroom function is the better fit, such as the Sargent 8XG04, a Grade 1 heavy duty storeroom knob lock with a 2-3/4 inch backset.
10) How far does a BEST 8K knob stick out from the door face?
The knob is 2-1/8 inch diameter with a 2-7/8 inch projection off the door. Worth checking against anything mounted close to the lock edge, a door closer arm, a pull on an adjacent leaf, or a narrow vestibule where two doors swing toward each other. Rose diameter is a separate choice: 2-9/16 inch concave, or 3-3/8 inch in concave, convex, or thick door versions.
11) What do I have to specify when ordering a BEST 8K knob lock?
Five things decide the part: 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 convex, or 3-3/8 inch concave thick door), strike (ANSI or standard), and finish. Beyond that, thick doors over 2 inch need the E trim, and the breakaway option is worth adding on vandal prone openings, it stops the lockset being turned off with a wrench.
12) What finishes does the BEST 8K knob lock come in, and is there one for a healthcare setting?
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, 626AM is the antimicrobial version of the standard satin chrome, so it matches 626 hardware elsewhere in the building while giving you the treated finish on the touch surfaces.
13) When would I order the 5 inch backset instead of the standard 2-3/4?
The 5 inch backset is for openings where the cross bore sits further in from the door edge, typically a wide stile or a door already prepped that way, often on aluminum or specialty commercial doors. On ordinary hollow metal and wood commercial doors, 2-3/4 inch is the standard commercial backset and the one to order. Measure from the door edge to the center of the existing 2-1/8 inch bore before you pick, because backset is not field adjustable on this chassis.
14) I need a Grade 1 knob lock but not a double cylinder. What else is there?
Within Grade 1 cylindrical knobs, the Falcon X101 is a heavy duty passage knobset with an interchangeable core that covers 1-3/8 inch to 2-1/4 inch doors, the Schlage D10S is a Grade 1 heavy duty passage latch with an orbit knob, and the Corbin Russwin CK4310 is a Grade 1 passage/closet lock for 1-3/8 inch to 2 inch doors. For keyed, the Sargent 8XG04 is a Grade 1 single cylinder storeroom with a 2-3/4 inch backset. Note that the X101 also takes an interchangeable core, which keeps a facility on one core platform across functions.
15) Is a Grade 2 or Grade 3 knob lock good enough, or do I need the Grade 1 BEST 8K?
It depends on the traffic behind the door. Grade 3 locks like the Cal-Royal BER00 entrance knob or the Pamex FTF Baron are built for 1-3/8 inch to 1-3/4 inch doors and light duty use, apartment interiors, closets, offices with low turnover. Grade 2 sits in the middle: the Dexter C2000 entry knob and the Corbin Russwin CK4410 are Grade 2 at the same thickness range. The 8K is Grade 1 heavy duty with solid brass or bronze knobs, which is what you want on a corridor, a stairwell, or anything cycling all day. Buying down a grade on a high traffic opening is where you end up replacing hardware in two years.
16) Can someone pull the knob off a BEST 8K and defeat the lock?
The design works against that. Cores have to be removed before the keyed knobs come off, so an attacker without the control key cannot get at the knob retention. There is no keeper hole on the keyed knobs, the inside rose snaps on with no exposed screws, and a friction insert in the rose resists it working loose over time. Where wrench attack is a real risk, spec the optional breakaway feature, which stops the lockset being overpowered.
17) What is a lighter duty alternative to a Grade 1 commercial knob lock for a low traffic office door?
The Sargent 6G04 is a Grade 2 standard duty storeroom/closet knob lock in the 6 Line Series with a single cylinder, and the Corbin Russwin CK4851 is an entrance/office cylindrical lock with a Global knob and a conventional cylinder covering 1-3/8 inch to 2 inch doors. Both are knob locks that key an office or storage door without the Grade 1 heavy duty chassis of the BEST 8K Series. The tradeoff is cycle life and keying: the 6G04 is standard duty, and the CK4851 uses a conventional cylinder rather than the small format interchangeable core the 8K is built around, so rekeying means pulling the cylinder rather than swapping a core.
18) Is the Schlage A170 dummy knob a substitute for a Grade 1 cylindrical knob lock?
No. The Schlage A170 in the A Series is a single dummy trim - a Grade 2 non-keyed knob with no latch and no chassis, meant to be surface mounted on an inactive leaf. The BEST 8K Series is a Grade 1 heavy duty cylindrical lock with a 2 1/8 inch bore chassis, a 9/16 inch throw deadlocking latch, and a keyed double cylinder function. A dummy trim will not latch a door, so it substitutes only for the pull side of a pair where the active leaf carries the locking hardware. The same applies to the Cal-Royal BA40 dummy knob and the Bravura Biloxi dummy knobset.
19) Can a residential keyed knob be used in place of a commercial Grade 1 knob lock on an apartment unit door?
The Kwikset 400P-CP Polo keyed entry knob is Grade 3 and covers 1-3/8 inch to 1-3/4 inch doors with a round corner adjustable latch and round corner strike, and the Master Lock BC01 in the BC Series is a Grade 3 biscuit knob keyed entry. Both are keyed knobs, but they sit two grades below the BEST 8K Series, which is Grade 1 commercial heavy duty. On a multi-tenant unit door under a master key system, the 8K also carries a small format interchangeable core, so a unit can be rekeyed by swapping the core rather than servicing the whole lock - which the Grade 3 entry knobs do not offer.
20) Which knob lock handles a classroom or storage door that only needs to be keyed from the outside?
The Dexter C2000 Series classroom knob lock is a Grade 2 keyed non-clutching ball knob for 1-3/8 inch to 1-3/4 inch doors, and the Sargent 8XG04 is a Grade 1 heavy duty storeroom/closet single cylinder knob lock with a 2-3/4 inch backset. Both key from one side only. The BEST 8K Series here is a double cylinder function, which puts a keyed cylinder on both faces - the right answer for a door that must be secured from inside as well, and more hardware than a one-sided classroom or storeroom opening calls for.
21) Is a knob lock the right part for a door that already has an exit device on it?
No. Where the door carries a panic or exit device, the outside trim is what gets specified - the Sargent 28C-KNOB is exit device trim with a knob and rose in entrance function for 1-3/4 inch doors, and the Imperial USA ED-BKL580 in the ED-500 Series is knob trim in storeroom function. Those mount to the exit device, not into a cylindrical bore. The BEST 8K Series is a complete cylindrical lock with its own chassis, latch, and strike, requiring a 2 1/8 inch bore and a 1 inch edge hole, and it is not trim for an exit device.
22) Is the BEST 8K knob lock electrified or does it need power?
Purely mechanical, no power, no wiring, no door loop or transfer hinge to coordinate. It locks and unlocks with a key on both sides regardless of building power, which is why it turns up on mechanical rooms, IT closets, and utility spaces where an access control failure cannot be allowed to open or strand a door.
23) I want the knobs to match the rest of the building. Does the BEST 8K come in a shape other than round?
Two knob styles, round and tulip, and both are available across the finish range. Tulip reads closer to the traditional profile you see on older institutional and multi-family openings, round is the plain commercial shape. Pair that with the rose choice, 2-9/16 inch or 3-3/8 inch, concave or convex, to cover any existing wear ring or paint line on the door face. The larger 3-3/8 inch rose is the one to pick when you are replacing older hardware that left a mark.
24) Is there a keyless knob lock that avoids issuing keys on a back service door?
The Lockey 3830 is a mechanical keyless combination knob lock with an auto-locking passage function, fitting doors from 1 3/16 inch to 2 inch. It secures the door with a pushbutton code instead of a key, so nothing has to be cut, issued, or collected. The BEST 8K Series takes the opposite approach: a Grade 1 heavy duty double cylinder knob lock keyed through a small format interchangeable core, so credential changes happen by swapping the core across the whole facility at once. Pick the 3830 where a single door needs a shared code and the 8K where the door belongs to a master keyed system.
25) What matches an existing satin chrome commercial knob lock on the rest of a floor?
The BEST 8K Series comes in 626 Satin Chrome and 625 Bright Chrome along with 605 Bright Brass, 606 Satin Brass, 611 Bright Bronze, 612 Satin Bronze, 613 Satin Bronze Oil-Rubbed, 619 Satin Nickel, 690 Statuary Dark Bronze, and 626AM Satin Chrome Antimicrobial, in round or tulip knob styles. Among comparable commercial knobsets, the Callan Roland is a Grade 2 entrance knobset in US15 Satin Nickel and the Bravura Dallas is a Grade 2 passage knobset in US4 Satin Brass. For a floor being standardized on one finish, the 8K carries the broader finish and knob style range to keep keyed and matching openings identical.
26) Which knob lock should go on a bathroom or bedroom door in a commercial building?
A privacy function knob is the part for that opening - the Dexter C2000 Series privacy knob is a Grade 2 non-keyed ball knob 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 over the same thickness range, and the Pamex FTF Baron is a Grade 3 privacy knob lockset. These lock from inside with no key outside. The BEST 8K Series in double cylinder function is keyed on both faces, which is not a privacy arrangement and is not appropriate for a restroom or bedroom door.
How fast can I get the BEST 8K37DR4ASTK626 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 8K37DR4ASTK626 come with a warranty?
Absolutely. The BEST 8K37DR4ASTK626 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 8K37DR4ASTK626?
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